Light-emitting device and input/output device

ABSTRACT

To provide a light-emitting device or an input/output device with little unevenness in display luminance or high reliability and to provide an input/output device with high detection sensitivity, a light-emitting device is configured to include a first substrate, a light-emitting element over the first substrate, a first conductive layer over the light-emitting element, a first insulating layer over the first conductive layer, a second conductive layer over the first insulating layer, and a second substrate over the second conductive layer. The light-emitting element includes a first electrode over the first substrate, a layer containing a light-emitting organic compound over the first electrode, and a second electrode over the layer containing a light-emitting organic compound. The second electrode is electrically connected to the first and second conductive layers. The first conductive layer and the second electrode transmit light emitted from the light-emitting element. The resistance of the second conductive layer is lower than that of the second electrode.

BACKGROUND OF THE INVENTION

1. Field of the Invention

One embodiment of the present invention relates to a light-emittingdevice and an input/output device, and particularly to a flexiblelight-emitting device and a flexible input/output device.

Note that one embodiment of the present invention is not limited to theabove technical field. One embodiment of the invention disclosed in thisspecification and the like relates to an object, a method, or amanufacturing method. One embodiment of the present invention relates toa process, a machine, manufacture, or a composition of matter.Specifically, examples of the technical field of one embodiment of thepresent invention disclosed in this specification include asemiconductor device, a display device, a light-emitting device, a powerstorage device, a memory device, an electronic device, a lightingdevice, an input device (e.g., a touch sensor), an output device, aninput/output device (e.g., a touch panel), a method for driving any ofthem, and a method for manufacturing any of them.

In this specification and the like, a semiconductor device generallymeans a device that can function by utilizing semiconductorcharacteristics. A semiconductor element such as a transistor, asemiconductor circuit, an arithmetic device, and a memory device areeach an embodiment of a semiconductor device. An imaging device, adisplay device, a liquid crystal display device, a light-emittingdevice, an electro-optical device, a power generation device (includinga thin-film solar cell and an organic thin-film solar cell), and anelectronic device may each include a semiconductor device.

2. Description of the Related Art

Light-emitting elements utilizing electroluminescence (EL), which arereferred to as EL elements, have features of the ease of being thinnerand lighter, high speed response to input signals, and capability of DClow voltage driving and have been expected to be applied to displaydevices and lighting devices.

Furthermore, a flexible device in which a functional element such as asemiconductor element, a display element, or a light-emitting element isprovided over a substrate having flexibility (hereinafter also referredto as flexible substrate) has been developed. Typical examples of theflexible device include a lighting device, an image display device, anda variety of semiconductor circuits including a semiconductor elementsuch as a transistor.

Patent Document 1 discloses a flexible active matrix light-emittingdevice in which an organic EL element and a transistor serving as aswitching element are provided over a film substrate.

Display devices are expected to be applied to a variety of uses andbecome diversified. For example, a smartphone and a tablet with a touchpanel are being developed as portable information appliances.

REFERENCE

Patent Document 1: Japanese Published Patent Application No. 2003-174153

SUMMARY OF THE INVENTION

An object of one embodiment of the present invention is to provide alight-emitting device or an input/output device with little unevennessin display luminance. Another object of one embodiment of the presentinvention is to provide a light-emitting device or an input/outputdevice with high reliability. Another object of one embodiment of thepresent invention is to provide an input/output device with highdetection sensitivity.

Another object of one embodiment of the present invention is tomanufacture a light-emitting device or an input/output device with asmall number of steps. Another object of one embodiment of the presentinvention is to manufacture a light-emitting device or an input/outputdevice with high yield.

Another object of one embodiment of the present invention is to providea flexible light-emitting device or a flexible input/output device.Another object of one embodiment of the present invention is to providea lightweight light-emitting device or a lightweight input/outputdevice. Another object of one embodiment of the present invention is toprovide a thin light-emitting device or a thin input/output device.Another object of one embodiment of the present invention is to achieveboth a reduction in thickness and high detection sensitivity of aninput/output device. Another object of one embodiment of the presentinvention is to provide a light-emitting device that can be used in alarge-size input/output device. Another object of one embodiment of thepresent invention is to provide a large-size input/output device.

Another object of one embodiment of the present invention is to providea light-emitting device or an input/output device with high resistanceto repeated bending. Another object of one embodiment of the presentinvention is to provide a novel semiconductor device, a novellight-emitting device, a novel display device, a novel input/outputdevice, a novel electronic device, or a novel lighting device.

Note that the description of these objects does not disturb theexistence of other objects. In one embodiment of the present invention,there is no need to achieve all the objects. Other objects will beapparent from and can be derived from the description of thespecification, the drawings, the claims, and the like.

One embodiment of the present invention is a light-emitting deviceincluding a first substrate, a light-emitting element over the firstsubstrate, a first conductive layer over the light-emitting element, afirst insulating layer over the first conductive layer, a secondconductive layer over the first insulating layer, and a second substrateover the second conductive layer. The light-emitting element includes afirst electrode over the first substrate, a first layer over the firstelectrode, and a second electrode over the first layer. The first layercontains a light-emitting organic compound. The second electrode, thefirst conductive layer, and the second conductive layer are electricallyconnected to each other. The first conductive layer and the secondelectrode transmit light emitted from the light-emitting element. Theresistance of the second conductive layer is lower than that of thesecond electrode.

Another embodiment of the present invention is a light-emitting deviceincluding a first substrate, a light-emitting element over the firstsubstrate, a first conductive layer over the light-emitting element, afirst insulating layer over the first conductive layer, a secondconductive layer over the first insulating layer, and a second substrateover the second conductive layer. The light-emitting element includes afirst electrode, a first layer, and a second electrode. The firstelectrode is placed over the first substrate. The first layer is placedover the first electrode. The second electrode is placed over the firstlayer. The second electrode is electrically connected to the firstconductive layer and the second conductive layer. The first conductivelayer includes a first portion and a second portion. The secondelectrode includes a third portion and a fourth portion. The resistanceof the first portion is lower than that of the third portion. The secondportion has a function of transmitting light emitted from thelight-emitting element. The fourth portion has a function oftransmitting light emitted from the light-emitting element.

In the light-emitting device with each of the above structures, hollowsealing or solid sealing may be used. For example, there may be a spacebetween the light-emitting element and the first conductive layer. Abonding layer may be provided between the light-emitting element and thefirst conductive layer.

The light-emitting device with each of the above structures may includea first transistor, in which case it is preferred that the firsttransistor be placed between the first substrate and the light-emittingelement and electrically connected to the light-emitting element.Specifically, a source electrode or a drain electrode of the firsttransistor is preferably electrically connected to the first electrode.

One embodiment of the present invention is an input/output deviceincluding the light-emitting device with one of the above structures, asecond transistor, and a capacitor. The second transistor and thecapacitor are electrically connected to each other. The secondtransistor and the capacitor are placed between the first conductivelayer and the second substrate. A gate electrode or source and drainelectrodes of the second transistor and the second conductive layer areformed on the same plane and contain the same material.

One embodiment of the present invention is an input/output deviceincluding a first substrate, a first transistor over the firstsubstrate, a light-emitting element over the first transistor, a bondinglayer over the light-emitting element, a first conductive layer over thebonding layer, a first insulating layer over the first conductive layer,a second conductive layer over the first insulating layer, a secondsubstrate over the second conductive layer, and a second transistor anda capacitor between the first conductive layer and the second substrate.The light-emitting element emits light toward the second substrate. Thefirst transistor and the light-emitting element are electricallyconnected to each other. The second transistor and the capacitor areelectrically connected to each other. The first conductive layeroverlaps with the light-emitting element. The first conductive layertransmits light emitted from the light-emitting element. The firstconductive layer is electrically connected to the second conductivelayer. The first conductive layer can be supplied with a predeterminedpotential. It is preferred that the second conductive layer be formed onthe same plane as and contain the same material as a gate electrode orsource and drain electrodes of the second transistor.

In each of the above structures, it is preferred that the capacitorinclude a pair of electrodes and a dielectric layer placed between thepair of electrodes, and that one of the pair of electrodes include anoxide conductor layer.

In each of the above structures, the first substrate and the secondsubstrate are preferably flexible.

The light-emitting device or the input/output device with each of theabove structures may include a coloring layer between the firstinsulating layer and the first conductive layer, in which case thecoloring layer preferably overlaps with the light-emitting element,specifically, there is preferably a region where the coloring layer andthe light-emitting element overlap with each other. When thelight-emitting device includes a bonding layer in contact with the firstconductive layer, the wettability of the first conductive layer to aresin used for the bonding layer is preferably higher than that of thecoloring layer.

The light-emitting device or the input/output device with each of theabove structures may include a first light-blocking layer between thefirst insulating layer and the first conductive layer, in which case thefirst light-blocking layer preferably overlaps with the secondconductive layer. Specifically, there is preferably a region where thefirst light-blocking layer and the second conductive layer overlap witheach other. When the light-emitting device includes a bonding layer incontact with the first conductive layer, the wettability of the firstconductive layer to a resin used for the bonding layer is preferablyhigher than that of the first light-blocking layer.

The light-emitting device or the input/output device with each of theabove structures may include a second light-blocking layer between thesecond substrate and the first conductive layer, in which case thesecond light-blocking layer preferably overlaps with the secondconductive layer. Specifically, there is preferably a region where thesecond light-blocking layer and the second conductive layer overlap witheach other.

Note that the light-emitting device or the input/output device of oneembodiment of the present invention is preferably flexible.

Note that the light-emitting device in this specification includes, inits category, a display device using a light-emitting element.Furthermore, the light-emitting device may be included in a module inwhich a light-emitting element is provided with a connector such as ananisotropic conductive film or a tape carrier package (TCP), a module inwhich a printed wiring board is provided at the end of a TCP, and amodule in which an integrated circuit (IC) is directly mounted on alight-emitting element by a chip on glass (COG) method. Thelight-emitting device may be included in lighting equipment or the like.

One embodiment of the present invention can provide a light-emittingdevice or an input/output device with little unevenness in displayluminance. Another embodiment of the present invention can provide alight-emitting device or an input/output device with high reliability.Another embodiment of the present invention can provide an input/outputdevice with high detection sensitivity.

Another embodiment of the present invention can manufacture aninput/output device with a small number of steps. Another embodiment ofthe present invention can manufacture an input/output device with highyield.

Another embodiment of the present invention can provide a flexiblelight-emitting device or a flexible input/output device. Anotherembodiment of the present invention can provide a lightweightlight-emitting device or a lightweight input/output device. Anotherembodiment of the present invention can provide a thin light-emittingdevice or a thin input/output device. Another embodiment of the presentinvention can achieve both a reduction in thickness and high detectionsensitivity of an input/output device. Another embodiment of the presentinvention can provide a light-emitting device that can be used in alarge-size input/output device. Another embodiment of the presentinvention can provide a large-size input/output device.

Another embodiment of the present invention can provide a method formanufacturing an input/output device with a small number of steps.

Another embodiment of the present invention can provide a light-emittingdevice or an input/output device with high resistance to repeatedbending. Another embodiment of the present invention can provide a novelsemiconductor device, a novel light-emitting device, a novel displaydevice, a novel input/output device, a novel electronic device, or anovel lighting device.

Note that the description of these effects does not disturb theexistence of other effects. One embodiment of the present invention doesnot necessarily achieve all the effects listed above. Other effects willbe apparent from and can be derived from the description of thespecification, the drawings, the claims, and the like.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIGS. 1A to 1C and 1D1 to 1D3 illustrate examples of a light-emittingdevice;

FIGS. 2A and 2B each illustrate an example of a light-emitting device;

FIGS. 3A and 3B each illustrate an example of a light-emitting device;

FIG. 4 illustrates an example of a light-emitting device;

FIGS. 5A and 5B each illustrate an example of an input/output device;

FIGS. 6A and 6B illustrate an example of an input/output device;

FIGS. 7A and 7B illustrate an example of configurations of a sensingcircuit and a converter, and FIGS. 7C1 and 7C2 illustrate an example ofa method for driving the sensing circuit;

FIGS. 8A to 8C illustrate an example of a sensing circuit;

FIGS. 9A to 9D illustrate configurations of an input/output device;

FIGS. 10A to 10C illustrate configurations of an input/output device;

FIGS. 11A and 11B illustrate an example of an input/output device;

FIGS. 12A and 12B illustrate an example of an input/output device;

FIG. 13 illustrates an example of an input/output device;

FIGS. 14A to 14D illustrate an example of a method for manufacturing alight-emitting device;

FIGS. 15A to 15D illustrate an example of a method for manufacturing alight-emitting device;

FIGS. 16A to 16D illustrate an example of a method for manufacturing alight-emitting device;

FIGS. 17A to 17C each illustrate an example of a method formanufacturing a light-emitting device;

FIGS. 18A to 18G each illustrate an example of an electronic device or alighting device; and

FIGS. 19A to 19I each illustrate an example of an electronic device.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments will be described in detail with reference to the drawings.Note that the present invention is not limited to the description below,and it is easily understood by those skilled in the art that variouschanges and modifications can be made without departing from the spiritand scope of the present invention. Accordingly, the present inventionshould not be interpreted as being limited to the content of theembodiments below.

Note that in the structures of the invention described below, the sameportions or portions having similar functions are denoted by the samereference numerals in different drawings, and description of suchportions is not repeated. In some cases, the same hatching pattern isused for portions having similar functions, and the portions are notdenoted by reference numerals.

The position, size, range, or the like of each structure illustrated indrawings and the like is not accurately represented in some cases foreasy understanding. Therefore, the disclosed invention is notnecessarily limited to the position, size, range, or the like disclosedin the drawings and the like.

Note that the terms “film” and “layer” can be interchanged with eachother depending on circumstances or situations. For example, in somecases, the term “conductive film” can be used instead of the term“conductive layer,” and the term “insulating layer” can be used insteadof the term “insulating film.”

Embodiment 1

In this embodiment, a light-emitting device of one embodiment of thepresent invention will be described with reference to drawings.

Although this embodiment shows an example in which an organic EL elementis used as a light-emitting element, a light-emitting device of oneembodiment of the present invention is not limited to this and mayinclude another light-emitting element.

In an active-matrix light-emitting device, a light-emitting element anda transistor are electrically connected to each other in each pixel, andlight emission of the light-emitting element of each pixel isindividually controlled. An organic EL element, which is an example of alight-emitting element, includes a layer containing a light-emittingorganic compound (also referred to as EL layer) between a lowerelectrode (also referred to as first electrode) and an upper electrode(also referred to as second electrode). A separate lower electrode isprovided for each pixel; that is, the lower electrodes in adjacentpixels are electrically insulated from each other. The upper electrodecan be used in common between a plurality of pixels.

In a large-area electrode such as an upper electrode used in commonbetween a plurality of pixels or an electrode of a large light-emittingelement for lighting application or the like, a potential drop may occurbecause of the resistance of the electrode. A large potential drop maycause a luminance gradient to be observed in display on thelight-emitting device.

The light-emitting element can have any of a top emission structure, abottom emission structure, and a dual emission structure. Thelight-emitting element preferably employs a top emission structure, inwhich case the light-emitting device can have a higher aperture ratiomore easily than that employing a bottom-emission light-emittingelement.

In the top-emission light-emitting element, an upper electrode needs totransmit light from the EL layer because light is extracted through theupper electrode. For example, the upper electrode can be formed using alight-transmitting conductive material such as indium tin oxide (ITO).Since such a light-transmitting conductive material has relatively highresistance among conductive materials used for electrodes, theaforementioned potential drop and luminance gradient in display on thelight-emitting device might be significant.

To avoid the issue, the electrode of the light-emitting element ispreferably electrically connected to an auxiliary electrode (alsoreferred to as auxiliary wiring) with lower resistance than theelectrode.

When an auxiliary electrode is formed over the light-emitting element,damage may be caused to the light-emitting element. For example, when aconductive layer to be the auxiliary electrode is formed by a sputteringmethod, thermal and physical damage is concerned. When the conductivelayer is processed by a photolithography method or the like, optical orthermal damage, melting of the light-emitting element due to an organicsolvent or the like in removal of a resist, or the like is concerned.

In view of the above, in one embodiment of the present invention, afirst electrode, an EL layer, and a second electrode are formed in thisorder over a first substrate, and a second conductive layer, aninsulating layer, and a first conductive layer are formed in this orderover a second substrate. In this structure, the first conductive layerand the second conductive layer are electrically connected to each otherthrough an opening in the insulating layer. The first substrate and thesecond substrate face each other so that the second electrode and thefirst conductive layer are connected to each other. Thus, the firstconductive layer, the second conductive layer, and the second electrodecan be electrically connected to each other.

In this manner, the conductive layer formed on the second substrate sideis electrically connected to the second electrode of the light-emittingelement formed over the first substrate, whereby the conductive layercan increase the conductivity of the second electrode. This structurecan suppress a potential drop due to the resistance of the secondelectrode and suppress unevenness in display luminance even in alight-emitting device including a large-area light-emitting element or atop-emission light-emitting element. Moreover, the auxiliary electrodeprotects the light-emitting element from damage, so that thelight-emitting device can have high reliability.

The first conductive layer is preferably formed extensively on the wholesurface of the light-emitting device by using a material that transmitslight from the light-emitting element. Accordingly, the area where thesecond electrode and the first conductive layer are in contact with eachother can be increased, and the contact resistance between the secondelectrode and the first conductive layer can be lowered. The secondconductive layer can use a wider range of materials than the firstconductive layer because it does not necessarily have transmittance. Thesecond conductive layer is formed using a material with lower resistancethan the second electrode and the first conductive layer, whereby avoltage drop of the second electrode can be further suppressed. Thus,one embodiment of the present invention achieves a light-emitting devicewith little unevenness in display luminance.

Note that in one embodiment of the present invention, the resistance ofat least one of the first and second conductive layers is lower thanthat of the second electrode.

Here, the resistances of the first and second conductive layers and thesecond electrode are obtained from(resistance×length)−(width×thickness).

In one embodiment of the present invention, the sheet resistance of atleast one of the first and second conductive layers is lower than thatof the second electrode.

Here, the sheet resistances of the first and second conductive layersand the second electrode are obtained from (resistance−thickness).

The first and second conductive layers and the second electrode maycontain materials with different resistances or materials with the sameresistance.

Specifically, a light-emitting device of one embodiment of the presentinvention includes a first substrate, a light-emitting element over thefirst substrate, a first conductive layer over the light-emittingelement, a first insulating layer over the first conductive layer, asecond conductive layer over the first insulating layer, and a secondsubstrate over the second conductive layer. The light-emitting elementincludes a first electrode over the first substrate, an EL layer overthe first electrode, and a second electrode over the EL layer. Thesecond electrode is electrically connected to the first conductive layerand the second conductive layer. The first conductive layer and thesecond electrode transmit light emitted from the light-emitting element.The resistance of the second conductive layer is lower than that of thesecond electrode.

In the above structure, the light-emitting element, the first conductivelayer, the first insulating layer, and the second conductive layer maybe included in a space formed by the first substrate, the secondsubstrate, and a bonding layer.

Alternatively, in the above structure, the first substrate and thesecond substrate may be attached to each other with a bonding layer.Specifically, the bonding layer for filling a space between the firstsubstrate and the second substrate may be positioned between thelight-emitting element and the first conductive layer. In this case, thewettability of the first conductive layer to a material of the bondinglayer is preferably high. High wettability to the material of thebonding layer can reduce air bubbles that enter when the first substrateand the second substrate are attached to each other, and the substratescan be attached with a high yield. Moreover, the light-emitting devicecan be highly reliable.

Examples of a light-emitting device of one embodiment of the presentinvention will be described below.

FIG. 1A is a plan view of a light-emitting device of one embodiment ofthe present invention. FIG. 1B is an enlarged view of a regionsurrounded by a dotted frame 80 in FIG. 1A. FIG. 2A is a cross-sectionalview along dashed-dotted line A1-A2 in FIG. 1A.

FIG. 1C is a plan view of a light-emitting device of another embodimentof the present invention. FIGS. 1D1 to 1D3 show examples of an enlargedview of a region surrounded by a dotted frame 81 in FIG. 1C. FIG. 2B,FIG. 3A, and FIG. 4 show examples of a cross-sectional view alongdashed-dotted line A3-A4 in FIG. 1C.

The light-emitting devices illustrated in FIGS. 1A and 1C each include alight-emitting unit 804 and a driver circuit unit 806. Light emittedfrom a light-emitting element included in the light-emitting unit 804 isextracted through a substrate 803. A flexible printed circuit (FPC) 808is connected to the light-emitting device. The light-emitting unit 804includes a conductive layer 853 functioning as an auxiliary electrode ofan upper electrode of the light-emitting element.

The light-emitting device in FIG. 1A includes a plurality of stripedconductive layers 853. The light-emitting device in FIG. 1C includes agrid-like conductive layer 853. There is no particular limitation on theplanar shape and the number of the conductive layers 853 functioning asan auxiliary electrode. The conductive layer 853 is preferablypositioned not to overlap with a light-emitting region of thelight-emitting element included in the light-emitting unit 804, in whichcase the auxiliary electrode can be provided without a reduction in thearea of the light-emitting region.

The enlarged views in FIGS. 1B and 1D1 to 1D3 show examples of a contactportion 855 for connecting the conductive layer 853 and a conductivelayer 851. Although there is no particular limitation on the positionand the number of the contact portions 855, the area where theconductive layers 851 and 853 are in contact with each other ispreferably large because the contact resistance between the conductivelayers 851 and 853 can be lowered accordingly. As illustrated in FIGS.1B and 1D1 to 1D3, one conductive layer 853 is connected to theconductive layer 851 through at least one contact portion 855. FIG. 1D1illustrates an example where the contact portions 855 are arranged inone direction. FIGS. 1D2 and 1D3 each illustrate an example where thecontact portions 855 are arranged in a plurality of directions.

Specific Example 1 of Cross-sectional Structure

The light-emitting device illustrated in FIG. 2A is a top-emissionlight-emitting device using a color filter method. In this embodiment,the light-emitting device can have a structure in which subpixels ofthree colors of red (R), green (G), and blue (B), for example, expressone color; a structure in which subpixels of four colors of R, G, B, andwhite (W) express one color; a structure in which subpixels of fourcolors of R, G, B, and yellow (Y) express one color; or the like. Thereis no particular limitation on color elements, and colors other than R,G, B, W, and Y may be used. For example, cyan or magenta may be used.

The light-emitting device in FIG. 2A includes a substrate 801, a bondinglayer 811, an insulating layer 813, a plurality of transistors, aconductive layer 857, an insulating layer 815, an insulating layer 817,a plurality of light-emitting elements, an insulating layer 821, abonding layer 822, the conductive layer 851, an insulating layer 852,the conductive layer 853, a coloring layer 845, a light-blocking layer847, an insulating layer 843, a bonding layer 841, and the substrate803. The bonding layer 822, the conductive layer 851, the insulatinglayer 852, the insulating layer 843, the bonding layer 841, and thesubstrate 803 transmit visible light.

In FIG. 2A, the light-emitting elements and the transistors included inthe light-emitting unit 804 and the driver circuit unit 806 are sealedwith the substrate 801, the substrate 803, and the bonding layer 822.

To fabricate the light-emitting device in FIG. 2A, first, a pair offormation substrates is prepared. The insulating layer 813, a transistor820, a light-emitting element 830, and the like are formed over one ofthe formation substrates. The insulating layer 843, the conductive layer851, the insulating layer 852, the conductive layer 853, and the likeare formed over the other formation substrate. Subsequently, theformation substrates are attached to each other with the bonding layer822. Then, the formation substrates are peeled, the substrate 801 isattached to the exposed insulating layer 813 with the bonding layer 811,and similarly, the substrate 803 is attached to the exposed insulatinglayer 843 with the bonding layer 841. Thus, the light-emitting device iscompleted. Note that a method for manufacturing a light-emitting deviceof one embodiment of the present invention will be described in detailin Embodiment 5.

When a material with low heat resistance (e.g., resin) is used for asubstrate, it is difficult to expose the substrate to high temperaturein the manufacturing process; thus, there is a limitation on conditionsfor forming a transistor and an insulating film over the substrate. Whena material with low moisture resistance (e.g., resin) is used for asubstrate of a light-emitting device, it is preferable to form a filmwith high moisture resistance at high temperatures between the substrateand a light-emitting element. Since a transistor and the like can beformed over a formation substrate with high heat resistance in themanufacturing method of this embodiment, a highly reliable transistorand an insulating film with sufficiently high moisture resistance can beformed at high temperatures. Then, the transistor and the insulatingfilm are transferred to a substrate with low heat resistance, whereby ahighly reliable light-emitting device can be manufactured. Thus, in oneembodiment of the present invention, a thin or/and lightweightlight-emitting device with high reliability can be provided.

Although there is no particular limitation on a material of thesubstrates 801 and 803, the substrates 801 and 803 are preferablyflexible. The use of flexible substrates achieves a flexiblelight-emitting device and can reduce the weight and thickness of thelight-emitting device.

In the light-emitting unit 804, the transistor 820 and thelight-emitting element 830 are provided over the substrate 801 with thebonding layer 811 and the insulating layer 813 placed therebetween. Thelight-emitting element 830 includes a first electrode 831 over theinsulating layer 817, an EL layer 833 over the first electrode 831, anda second electrode 835 over the EL layer 833. The first electrode 831 iselectrically connected to a source electrode or a drain electrode of thetransistor 820. An end portion of the first electrode 831 is coveredwith the insulating layer 821. The first electrode 831 preferablyreflects visible light. The second electrode 835 transmits visiblelight.

In the light-emitting unit 804, the coloring layer 845 overlapping thelight-emitting element 830 and the light-blocking layer 847 overlappingthe insulating layer 821 are provided. The coloring layer 845 and thelight-blocking layer 847 are covered with the conductive layer 851. Thespace between the light-emitting element 830 and the conductive layer851 is filled with the bonding layer 822.

The conductive layer 851 is connected to the conductive layer 853through an opening in the insulating layer 852. The conductive layer 851is also connected to the second electrode 835. That is, the secondelectrode 835, the conductive layer 851, and the conductive layer 853are electrically connected to each other. Electrically connecting thesecond electrode 835, the conductive layer 851, and the conductive layer853 can suppress a voltage drop of the second electrode 835, therebyreducing unevenness in display luminance of the light-emitting device.Note that the insulating layer 852 is not necessarily provided. Anovercoat may be provided between the conductive layer 851 and thecoloring layer 845 or the light-blocking layer 847.

Since the conductive layer 851 is formed using a material that transmitlight from the light-emitting element 830, the conductive layer 851 canbe formed extensively on the whole surface of the light-emitting device.Accordingly, the area where the second electrode 835 and the conductivelayer 851 are in contact with each other can be increased, and thecontact resistance between the second electrode 835 and the conductivelayer 851 can be lowered. Furthermore, the area where the conductivelayers 851 and 853 are in contact with each other is preferably largebecause the contact resistance between the conductive layers 851 and 853can be lowered accordingly.

The conductive layer 853 does not necessarily have transmittance becauseit does not overlap a light-emitting region of the light-emittingelement 830 (i.e., it overlaps the insulating layer 821). For thisreason, the conductive layer 853 can be formed using a wider range ofmaterials than the conductive layer 851. When the conductive layer 853is formed using a material with lower resistance than the secondelectrode 835 and the conductive layer 851, a voltage drop of the secondelectrode 835 can be further suppressed.

A conductive film that transmits visible light and can be used for theconductive layer 851 can be formed using indium oxide, ITO, indium zincoxide, zinc oxide, or zinc oxide to which gallium is added, for example.It is also possible to use a film of a metal material such as gold,silver, platinum, magnesium, nickel, tungsten, chromium, molybdenum,iron, cobalt, copper, palladium, or titanium; an alloy containing any ofthese metal materials; or a nitride of any of these metal materials(e.g., titanium nitride) when the film is thin enough to have alight-transmitting property. Alternatively, a stack of any of the abovematerials can be used for the conductive film. For example, a stackedfilm of ITO and an alloy of silver and magnesium is preferably used, inwhich case conductivity can be increased. Further alternatively,graphene or the like may be used.

The conductive layer 853 can be formed with a single-layer structure ora stacked-layer structure using any of metal materials such asmolybdenum, titanium, chromium, tantalum, tungsten, aluminum, copper,neodymium, and scandium, and an alloy material containing any of theseelements. The conductive layer 853 may be formed using a conductivemetal oxide. As the conductive metal oxide, indium oxide (e.g., In₂O₃),tin oxide (e.g., SnO₂), zinc oxide (ZnO), ITO, indium zinc oxide (e.g.,In₂O₃—ZnO), or any of these metal oxide materials in which silicon oxideis contained can be used. Moreover, the conductive layer 853 may beformed using a material for another conductive layer such as theconductive layer 851.

Note that each of the conductive layers 851 and 853 may have asingle-layer structure or a stacked-layer structure.

The substrate 801 and the substrate 803 are attached to each other withthe bonding layer 822. The bonding layer 822 is positioned between thelight-emitting element 830 and the conductive layer 851. In this case,the wettability of the conductive layer 851 to a material of the bondinglayer 822 is preferably high. High wettability to the material of thebonding layer 822 can reduce air bubbles entering when the pair offormation substrates are attached to each other, and the substrates canbe attached with a high yield. Moreover, the light-emitting device canbe highly reliable. For example, when a resin is used for the bondinglayer 822, the conductive layer 851 is preferably an oxide conductivefilm such as an ITO film or a metal film such as an Ag film that is thinenough to transmit light, in particular preferably an ITO film. Theconductive layer 851 may be provided only in the light-emitting unit804, provided in the light-emitting unit 804 and the driver circuit unit806, or provided on the entire surface over the insulating layer 843.

The insulating layer 815 has an effect of preventing diffusion ofimpurities into a semiconductor included in the transistor. Moreover,the insulating layer 817 is preferably an insulating layer with aplanarization function in order to reduce surface unevenness due to thetransistor.

In the driver circuit unit 806, a plurality of transistors are providedover the substrate 801 with the bonding layer 811 and the insulatinglayer 813 positioned therebetween. FIG. 2A illustrates one of thetransistors included in the driver circuit unit 806.

The insulating layer 813 and the substrate 801 are attached with thebonding layer 811. The insulating layer 843 and the substrate 803 areattached with the bonding layer 841. The insulating layer 813 and theinsulating layer 843 are preferably highly resistant to moisture, inwhich case impurities such as water can be prevented from entering thelight-emitting element 830 or the transistor 820, leading to higherreliability of the light-emitting device.

The conductive layer 857 is electrically connected to an external inputterminal through which a signal (e.g., a video signal, a clock signal, astart signal, or a reset signal) or a potential from the outside istransmitted to the driver circuit unit 806. Here, an example in whichthe FPC 808 is provided as the external input terminal is described. Toprevent an increase in the number of fabrication steps, the conductivelayer 857 is preferably formed using the same material and the same stepas those of the electrode or the wiring in the light-emitting unit orthe driver circuit unit. Here, an example is described in which theconductive layer 857 is formed using the same material and the same stepas those of the electrodes of the transistor 820.

In the light-emitting device in FIG. 2A, the FPC 808 is positioned abovethe substrate 803. A connector 825 is connected to the conductive layer857 through an opening provided in the substrate 803, the bonding layer841, the insulating layer 843, the bonding layer 822, the insulatinglayer 817, and the insulating layer 815. Furthermore, the connector 825is connected to the FPC 808. That is, the FPC 808 and the conductivelayer 857 are electrically connected to each other through the connector825. When the conductive layer 857 and the substrate 803 overlap witheach other, an opening formed in the substrate 803 (or the use of asubstrate with an opening) allows the conductive layer 857, theconnector 825, and the FPC 808 to be electrically connected to eachother.

Note that a user of the light-emitting device in FIG. 2A may recognizethe conductive layer 853 or the like. For this reason, a film with lowreflectivity or a light-blocking film may be provided between thesubstrate 803 and the conductive layer 853. Moreover, a conductive filmwith low reflectivity may be used as the conductive layer 853.

Specific Example 2 of Cross-sectional Structure

FIG. 2B illustrates a top-emission light-emitting device using a colorfilter method, which is different from that in FIG. 2A. In subsequentspecific examples, differences from Specific Example 1 are described indetail, and description of the same points is omitted.

The light-emitting device in FIG. 2B includes the substrate 801, aninsulating layer 812, a plurality of transistors, the conductive layer857, the insulating layer 815, the insulating layer 817, a plurality oflight-emitting elements, the insulating layer 821, a bonding layer 846,the conductive layer 851, the insulating layer 852, the conductive layer853, the coloring layer 845, the light-blocking layer 847, an insulatinglayer 842, and the substrate 803. The conductive layer 851, theinsulating layer 852, the insulating layer 842, and the substrate 803transmit visible light.

In FIG. 2B, the light-emitting elements and the transistors included inthe light-emitting unit 804 and the driver circuit unit 806 are sealedin a space 848 formed by the substrate 801, the substrate 803, and thebonding layer 846. The space 848 may be filled with an inert gas such asa rare gas or a nitrogen gas or a solid such as organic resin, or may bein a reduced-pressure atmosphere. The amount of impurities such as wateror oxygen is preferably small in the space 848, in which case thereliability of the light-emitting elements is increased.

As in the light-emitting device illustrated in FIG. 2B, elements such asa transistor and a light-emitting element, a conductive layer, and aninsulating layer may be provided over a substrate without a bondinglayer placed therebetween. In that case, a substrate with heatresistance high enough to withstand the process temperature in themanufacturing process, such as a glass substrate, is used as thesubstrate 801 and the substrate 803. Then, the insulating layer 812, thetransistor 820, and the like are formed directly over the substrate 801.Similarly, the insulating layer 842, the conductive layer 853, and thelike are formed directly over the substrate 803.

Specific Example 3 of Cross-sectional Structure

FIG. 3A illustrates a top-emission light-emitting device using a colorfilter method, which is different from that in FIG. 2A.

The light-emitting device in FIG. 3A includes the substrate 801, thebonding layer 811, the insulating layer 813, a plurality of transistors,the conductive layer 857, the insulating layer 815, an insulating layer817 a, an insulating layer 817 b, a conductive layer 856, a plurality oflight-emitting elements, the insulating layer 821, the bonding layer822, a spacer 823, the conductive layer 851, an overcoat 849, theinsulating layer 852, the conductive layer 853, the coloring layer 845,the light-blocking layer 847, the insulating layer 843, the bondinglayer 841, and the substrate 803. The bonding layer 822, the conductivelayer 851, the overcoat 849, the insulating layer 852, the insulatinglayer 843, the bonding layer 841, and the substrate 803 transmit visiblelight.

The light-emitting device in FIG. 3A includes the spacer 823 over theinsulating layer 821. The spacer 823 can adjust the distance between thesubstrate 801 and the substrate 803.

The first electrode 831 of the light-emitting element 830 iselectrically connected to the conductive layer 856 and the sourceelectrode or the drain electrode of the transistor 820.

In the light-emitting device in FIG. 3A, the substrate 801 and thesubstrate 803 have different sizes. The FPC 808 is positioned over theinsulating layer 843 and does not overlap the substrate 803. Theconnector 825 is connected to the conductive layer 857 through anopening provided in the insulating layer 843, the conductive layer 851,the bonding layer 822, the insulating layer 817 a, and the insulatinglayer 815. There is no limitation on the material for the substrate 803because an opening does not need to be formed in the substrate 803.

In one embodiment of the present invention, the light-emitting elementmay include the first electrode 831, an optical adjustment layer 832,the EL layer 833, and the second electrode 835 as illustrated in FIG.3B. The optical adjustment layer 832 is preferably formed using alight-transmitting conductive material.

Owing to the combination of the coloring layer and a microcavitystructure (the optical adjustment layer 832), light with high colorpurity can be extracted from the light-emitting device of one embodimentof the present invention. The thickness of the optical adjustment layer832 may be varied depending on the color of the pixel.

Alternatively, instead of providing the optical adjustment layer 832,optical adjustment may be performed by varying the thickness of theelectrode or the EL layer included in the light-emitting element betweenpixels. Although FIG. 3A shows an example where the light-blocking layer847 is provided between the coloring layers, the light-blocking layer847 may not be provided between the coloring layers.

The overcoat 849 covering the light-blocking layer 847 and the coloringlayer 845 may be provided. The overcoat 849 may be positioned betweenthe conductive layer 851 and the light-blocking layer 847 or thecoloring layer 845. Note that the overcoat 849 is not necessarilyprovided. The overcoat 849 may be provided only in the light-emittingunit 804, provided in the light-emitting unit 804 and the driver circuitunit 806, or provided on the entire surface over the insulating layer843. In FIG. 3A, the overcoat 849 is provided in the light-emitting unit804 and the driver circuit unit 806, and in addition, the conductivelayer 851 is provided on the entire surface over the insulating layer843 and is electrically insulated from the connector 825. These aremerely examples, and one embodiment of the present invention is notlimited to these examples.

Specific Example 4 of Cross-sectional Structure

FIG. 4 illustrates a top-emission light-emitting device using a separatecoloring method.

The light-emitting device in FIG. 4 includes the substrate 801, thebonding layer 811, the insulating layer 813, a plurality of transistors,the conductive layer 857, the insulating layer 815, the insulating layer817, a plurality of light-emitting elements, the insulating layer 821,the spacer 823, the bonding layer 822, the conductive layer 851, theinsulating layer 852, the conductive layer 853, the insulating layer843, the bonding layer 841, and the substrate 803. The bonding layer822, the conductive layer 851, the insulating layer 852, the insulatinglayer 843, the bonding layer 841, and the substrate 803 transmit visiblelight.

Examples of Materials

Next, materials that can be used for the light-emitting device will bedescribed. Note that description of the components already described inthis specification is omitted in some cases.

For the substrate, glass, quartz, an organic resin, a metal, an alloy,or the like can be used. The substrate through which light from thelight-emitting element is extracted is formed using a material thattransmits the light.

It is particularly preferable to use a flexible substrate. For example,it is possible to use glass, a metal, or an alloy that is thin enough tohave flexibility, or an organic resin.

An organic resin, which has a smaller specific gravity than glass, ispreferably used for the flexible substrate, in which case thelight-emitting device can be lighter in weight than that using glass.

A material with high toughness is preferably used for the substrate. Inthat case, a robust light-emitting device with high impact resistancecan be provided. For example, when an organic resin substrate or a thinmetal or alloy substrate is used, the light-emitting device can belighter in weight and more robust than that using a glass substrate.

A metal material and an alloy material, which have high thermalconductivity, are preferred because they can easily conduct heat to thewhole substrate and accordingly can prevent a local temperature rise inthe light-emitting device. The thickness of a substrate using a metalmaterial or an alloy material ranges preferably from 10 μm to 200 μm,more preferably from 20 μm to 50 μm.

Although there is no particular limitation on a material for the metalsubstrate and the alloy substrate, it is preferable to use, for example,aluminum, copper, nickel, or a metal alloy such as an aluminum alloy orstainless steel.

Furthermore, when a material with high thermal emissivity is used forthe substrate, the surface temperature of the light-emitting device canbe prevented from rising, leading to prevention of breakage or adecrease in reliability of the light-emitting device. For example, thesubstrate may have a stacked-layer structure of a metal substrate and alayer with high thermal emissivity (e.g., a layer formed using a metaloxide or a ceramic material).

Examples of a material having flexibility and a light-transmittingproperty include polyester resins such as polyethylene terephthalate(PET) and polyethylene naphthalate (PEN), a polyacrylonitrile resin, apolyimide resin, a polymethyl methacrylate resin, a polycarbonate (PC)resin, a polyethersulfone (PES) resin, a polyamide resin, a cycloolefinresin, a polystyrene resin, a polyamide imide resin, and a polyvinylchloride resin. In particular, a material with a low coefficient ofthermal expansion is preferred, and for example, a polyamide imideresin, a polyimide resin, or PET can be suitably used. It is alsopossible to use a substrate in which a fibrous body is impregnated witha resin (also referred to as prepreg) or a substrate whose coefficientof thermal expansion is reduced by mixing an organic resin with aninorganic filler.

The flexible substrate may have a stacked-layer structure in which ahard coat layer by which a surface of the device is protected fromdamage (e.g., a silicon nitride layer), a layer that can dispersepressure (e.g., an aramid resin layer), or the like is stacked over alayer of any of the above-mentioned materials.

The flexible substrate may be formed by stacking a plurality of layers.When a glass layer is used, a barrier property against water and oxygencan be improved and thus a reliable light-emitting device can beprovided.

For example, it is possible to use a flexible substrate in which a glasslayer, a bonding layer, and an organic resin layer are stacked from theside closer to a light-emitting element. The thickness of the glasslayer ranges from 20 μm to 200 μm, preferably from 25 μm to 100 μm. Withsuch a thickness, the glass layer can have both high flexibility and ahigh barrier property against water and oxygen. The thickness of theorganic resin layer ranges from 10 μm to 200 μm, preferably from 20 umto 50 μm. Providing such an organic resin layer outside the glass layer,occurrence of a crack or a break in the glass layer can be suppressedand mechanical strength can be improved. With the substrate using such acomposite material of a glass material and an organic resin, a flexiblelight-emitting device with high reliability can be provided.

For the bonding layer, a variety of curable adhesives such as aphotocurable adhesive (e.g., an ultraviolet curable adhesive), areactive curable adhesive, a thermosetting adhesive, and an anaerobicadhesive can be used. Examples of these adhesives include an epoxyresin, an acrylic resin, a silicone resin, a phenol resin, a polyimideresin, an imide resin, a polyvinyl chloride (PVC) resin, a polyvinylbutyral (PVB) resin, and an ethylene vinyl acetate (EVA) resin. Amaterial with low moisture permeability, such as an epoxy resin, isparticularly preferred. Alternatively, a two-component resin may beused. An adhesive sheet or the like may be used.

Furthermore, the resin may include a drying agent. For example, it ispossible to use a substance that adsorbs moisture by chemicaladsorption, such as oxide of an alkaline earth metal (e.g., calciumoxide or barium oxide). Alternatively, it is possible to use a substancethat adsorbs moisture by physical adsorption, such as zeolite or silicagel. The drying agent is preferably included because it can preventimpurities such as moisture from entering the functional element,thereby improving the reliability of the light-emitting device.

When a filler with a high refractive index or a light scattering memberis mixed into the resin, the efficiency of light extraction from thelight-emitting element can be improved. For example, titanium oxide,barium oxide, zeolite, or zirconium can be used.

There is no particular limitation on the structure of the transistors inthe light-emitting device. For example, a forward staggered transistoror an inverted staggered transistor may be used. A top-gate transistoror a bottom-gate transistor may be used. There is no particularlimitation on a semiconductor material used for the transistors, and anoxide semiconductor, silicon, germanium, or an organic semiconductor canbe used, for example.

There is no particular limitation on the crystallinity of asemiconductor material used for the transistors, and an amorphoussemiconductor or a semiconductor having crystallinity (amicrocrystalline semiconductor, a polycrystalline semiconductor, asingle crystal semiconductor, or a semiconductor partly includingcrystal regions) may be used. A semiconductor having crystallinity ispreferably used, in which case deterioration of the transistorcharacteristics can be suppressed.

For a semiconductor layer, an element belonging to Group 4, a compoundsemiconductor, or an oxide semiconductor can be used, for example.Specifically, a semiconductor containing silicon, a semiconductorcontaining gallium arsenide, or an oxide semiconductor containing indiumcan be used.

An oxide semiconductor is preferably used as a semiconductor where achannel of the transistor is formed. In particular, an oxidesemiconductor having a wider band gap than silicon is preferably used. Asemiconductor material having a wider band gap and a lower carrierdensity than silicon is preferably used because off-state leakagecurrent of the transistor can be reduced.

For example, the oxide semiconductor preferably contains at least indium(In) or zinc (Zn). More preferably, the oxide semiconductor isIn—M—Zn-based oxide (M is a metal such as Al, Ti, Ga, Ge, Y, Zr, Sn, La,Ce, or Hf).

As the semiconductor layer, it is preferable to use an oxidesemiconductor film including a plurality of crystal parts. Specifically,the c-axes of the crystal parts are oriented substantially perpendicularto a surface on which the semiconductor layer is formed or the topsurface of the semiconductor layer, and adjacent crystal parts have nograin boundary.

Such an oxide semiconductor without grain boundary prevents a crack ofan oxide semiconductor film from being caused by stress generated whenthe light-emitting device is bent. Consequently, such an oxidesemiconductor is preferably used for a flexible light-emitting devicethat is bent when used.

The use of such an oxide semiconductor for the semiconductor layerachieves a highly reliable transistor with little change in theelectrical characteristics.

Charge accumulated in a capacitor through a transistor can be retainedfor a long time because of low off-state current of the transistor. Theuse of such a transistor in pixels allows a driver circuit to stop whilethe gray level of an image displayed on display regions of the pixels ismaintained. As a result, a light-emitting device with extremely lowpower consumption is obtained.

Alternatively, silicon is preferably used as a semiconductor in which achannel of a transistor is formed. Silicon may be amorphous silicon butis preferably silicon having crystallinity, such as microcrystallinesilicon, polycrystalline silicon, or single crystal silicon. Inparticular, polycrystalline silicon can be formed at a lower temperaturethan single crystal silicon and has higher field-effect mobility andhigher reliability than amorphous silicon. When such a polycrystallinesemiconductor is used for a pixel, the aperture ratio of the pixel canbe increased. Even when pixels are provided at very high density, a gatedriver circuit and a source driver circuit can be formed over asubstrate where the pixels are formed, so that the number of componentsof an electronic device can be reduced.

For stable characteristics of the transistor, a base film is preferablyprovided. The base film can be formed with a single-layer structure or astacked-layer structure using an inorganic insulating film such as asilicon oxide film, a silicon nitride film, a silicon oxynitride film,or a silicon nitride oxide film. The base film can be formed bysputtering, chemical vapor deposition (CVD) such as a plasma-enhancedCVD, thermal CVD, or metal organic CVD (MOCVD), atomic layer deposition(ALD), coating, printing, or the like. Note that the base film is notnecessarily provided. In each of the above structure examples, theinsulating layer 813 can also serve as a base film of the transistor.

As the light-emitting element, a self-luminous element can be used, andan element whose luminance is controlled by current or voltage isincluded in the category of the light-emitting element. For example, alight-emitting diode (LED), an organic EL element, or an inorganic ELelement can be used.

A conductive film that transmits visible light is used for the electrodethrough which light from the light-emitting element is extracted. Aconductive film that reflects visible light is preferably used for theelectrode through which light is not extracted.

The conductive film that transmits visible light can be formed using,for example, indium oxide, indium tin oxide (ITO), indium zinc oxide,zinc oxide, or zinc oxide to which gallium is added. It is also possibleto use a film of a metal material such as gold, silver, platinum,magnesium, nickel, tungsten, chromium, molybdenum, iron, cobalt, copper,palladium, or titanium; an alloy containing any of these metalmaterials; or a nitride of any of these metal materials (e.g., titaniumnitride) when the film is thin enough to have a light-transmittingproperty. Alternatively, a stack of any of the above materials can beused as the conductive film. For example, a stacked film of ITO and analloy of silver and magnesium is preferably used, in which caseconductivity can be increased. Further alternatively, graphene or thelike may be used.

For the conductive film that reflects visible light, a metal materialsuch as aluminum, gold, platinum, silver, nickel, tungsten, chromium,molybdenum, iron, cobalt, copper, or palladium or an alloy containingany of these metal materials can be used, for example. Lanthanum,neodymium, germanium, or the like may be added to the metal material orthe alloy. Moreover, the conductive film can be formed using an alloycontaining aluminum (an aluminum alloy) such as an alloy of aluminum andtitanium, an alloy of aluminum and nickel, or an alloy of aluminum andneodymium; or an alloy containing silver such as an alloy of silver andcopper, an alloy of silver, palladium, and copper, or an alloy of silverand magnesium. An alloy of silver and copper is preferable because ofits high heat resistance. When a metal film or a metal oxide film isstacked on an aluminum alloy film, oxidation of the aluminum alloy filmcan be suppressed. Examples of a material for the metal film or themetal oxide film are titanium and titanium oxide. Alternatively, theconductive film having a property of transmitting visible light and afilm containing any of the above metal materials may be stacked. Forexample, it is possible to use a stacked film of silver and ITO or astacked film of an alloy of silver and magnesium and ITO.

Each of the electrodes can be formed by an evaporation method or asputtering method. Alternatively, a discharging method such as anink-jet method, a printing method such as a screen printing method, or aplating method can be used.

When a voltage higher than the threshold voltage of the light-emittingelement is applied between the first electrode 831 and the secondelectrode 835, holes are injected to the EL layer 833 from the anodeside and electrons are injected to the EL layer 833 from the cathodeside. The injected electrons and holes are recombined in the EL layer833 and a light-emitting substance contained in the EL layer 833 emitslight.

The EL layer 833 includes at least a light-emitting layer. In additionto the light-emitting layer, the EL layer 833 may further include one ormore layers containing any of a substance with a high hole-injectionproperty, a substance with a high hole-transport property, ahole-blocking material, a substance with a high electron-transportproperty, a substance with a high electron-injection property, asubstance with a bipolar property (a substance with a highelectron-transport property and a high hole-transport property), and thelike.

For the EL layer 833, either a low molecular compound or a highmolecular compound can be used, and an inorganic compound may be used.Each of the layers included in the EL layer 833 can be formed by any ofthe following methods: an evaporation method (including a vacuumevaporation method), a transfer method, a printing method, an ink-jetmethod, a coating method, and the like.

The light-emitting element is preferably provided between a pair ofinsulating films that are highly resistant to moisture, in which caseimpurities such as water can be prevented from entering thelight-emitting element, thereby preventing a decrease in the reliabilityof the light-emitting device.

Examples of the insulating film with high resistance to moisture includea film containing nitrogen and silicon (e.g., a silicon nitride film anda silicon nitride oxide film) and a film containing nitrogen andaluminum (e.g., an aluminum nitride film). Alternatively, a siliconoxide film, a silicon oxynitride film, an aluminum oxide film, or thelike may be used.

For example, the moisture vapor transmission rate of the insulating filmwith high resistance to moisture is lower than or equal to 1×10⁻⁵[g/(m²·day)], preferably lower than or equal to 1×10⁻⁶ [g/(m²·day)],further preferably lower than or equal to 1×10⁻⁷ [g/(m²·day)], stillfurther preferably lower than or equal to 1×10⁻⁸ [g/(m²·day)].

Insulating films with high resistance to moisture are preferably used asthe insulating layer 813 and the insulating layer 843.

As each of the insulating layers 812, 815, and 842, an inorganicinsulating film such as a silicon oxide film, a silicon oxynitride film,a silicon nitride film, a silicon nitride oxide film, or an aluminumoxide film can be used, for example. For each of the insulating layers817, 817 a, 817 b, and 852, an organic material such as polyimide,acrylic, polyamide, polyimide amide, or a benzocyclobutene-based resincan be used, for example. Alternatively, a low dielectric constantmaterial (low-k material) or the like can be used. Furthermore, each ofthe insulating layers may be formed by stacking a plurality ofinsulating films.

The insulating layer 821 is formed using an organic insulating materialor an inorganic insulating material. As a resin, a polyimide resin, apolyamide resin, an acrylic resin, a siloxane resin, an epoxy resin, ora phenol resin can be used, for example. It is particularly preferablethat the insulating layer 821 be formed to have an inclined sidewallwith continuous curvature by using a photosensitive resin material.

There is no particular limitation on the method for forming theinsulating layer 821. A photolithography method, a sputtering method, anevaporation method, a droplet discharging method (e.g., an ink-jetmethod), a printing method (e.g., screen printing or off-set printing),or the like may be used.

The spacer 823 can be formed using an inorganic insulating material, anorganic insulating material, a metal material, or the like. As theinorganic insulating material and the organic insulating material, avariety of materials that can be used for the aforementioned insulatinglayers can be used, for example. As the metal material, titanium,aluminum, or the like can be used. When the spacer 823 containing aconductive material and the second electrode 835 are electricallyconnected to each other, a potential drop due to the resistance of thesecond electrode 835 can be suppressed. The spacer 823 may have atapered shape or an inverse tapered shape.

A conductive layer functioning as an electrode of the transistor, awiring, an auxiliary wiring of the light-emitting element, or the likein the light-emitting device can be formed with a single-layer structureor a stacked-layer structure using any of a metal material such asmolybdenum, titanium, chromium, tantalum, tungsten, aluminum, copper,neodymium, and scandium and an alloy material containing any of theseelements, for example. The conductive layer may be formed using aconductive metal oxide such as indium oxide (e.g., In₂O₃), tin oxide(e.g., SnO₂), zinc oxide (ZnO), ITO, indium zinc oxide (e.g.,In₂O₃—ZnO), or any of these metal oxide materials containing siliconoxide.

The coloring layer 845 is a colored layer that transmits light in aspecific wavelength range. For example, a red (R) color filter fortransmitting light in a red wavelength range, a green (G) color filterfor transmitting light in a green wavelength range, and a blue (B) colorfilter for transmitting light in a blue wavelength range can be used.Each coloring layer is formed in a desired position with any of variousmaterials by a printing method, an ink-jet method, an etching methodusing photolithography, or the like. The coloring layer can be formedusing a metal material, pigment, dye, or the like.

The light-blocking layer 847 is provided between adjacent coloringlayers. The light-blocking layer blocks light emitted from an adjacentlight-emitting element to prevent color mixture between adjacentlight-emitting elements. Here, the coloring layer is provided such thatits end portion overlaps with the light-blocking layer, whereby lightleakage can be reduced. For the light-blocking layer, a material thatblocks light from the light-emitting element can be used; for example, ablack matrix can be formed using carbon black; a metal oxide; acomposite oxide containing a solid solution of a plurality of metaloxides; or a resin material containing a metal material, pigment, ordye. Note that it is preferable to provide the light-blocking layer in aregion other than the light-emitting unit, such as the driver circuitunit, in which case undesired leakage of guided light or the like can besuppressed.

The overcoat 849 covering the coloring layer and the light-blockinglayer may be provided. The overcoat can prevent impurities and the likecontained in the coloring layer from being diffused into thelight-emitting element. The overcoat is formed with a material thattransmits light emitted from the light-emitting element; for example, itis possible to use an inorganic insulating film such as a siliconnitride film or a silicon oxide film, an organic insulating film such asan acrylic film or a polyimide film, or a stacked layer of an organicinsulating film and an inorganic insulating film.

For the connector 825, it is possible to use a paste-like or sheet-likematerial that is obtained by mixing metal particles into a thermosettingresin and exhibits anisotropic electrical conductivity bythermocompression bonding. As the metal particles, particles in whichtwo or more kinds of metals are layered, for example, nickel particlescoated with gold are preferably used.

Note that there is no particular limitation on the light-emittingelement included in the light-emitting device of one embodiment of thepresent invention. In addition, one embodiment of the present inventioncan also be applied to a display device including a display element.

Note that in this specification and the like, a display element, adisplay device including a display element, a light-emitting element,and a light-emitting device including a light-emitting element canemploy various modes or can include various elements. A display element,a display device, a light-emitting element, or a light-emitting deviceincludes at least one of the following, for example: an EL element(e.g., an EL element including organic and inorganic materials, anorganic EL element, and an inorganic EL element), an LED (e.g., a whiteLED, a red LED, a green LED, and a blue LED), a transistor (a transistorthat emits light depending on current), an electron emitter, a liquidcrystal element, electronic ink, an electrophoretic element, a gratinglight valve (GLV), a plasma display panel (PDP), a display element usingmicro electro mechanical system (MEMS), a digital micromirror device(DMD), a digital micro shutter (DMS), an interferometric modulator(IMOD) element, a MEMS shutter display element, anoptical-interference-type MEMS display element, an electrowettingelement, a piezoelectric ceramic display, and a display element using acarbon nanotube. Other than the above, a display medium whose contrast,luminance, reflectance, transmittance, or the like is changed byelectric or magnetic action may be included. An example of a displaydevice having EL elements is an EL display. Examples of a display deviceincluding electron emitters are a field emission display (FED) and anSED-type flat panel display (SED: surface-conduction electron-emitterdisplay). An example of a display device including liquid crystalelements is a liquid crystal display (e.g., a transmissive liquidcrystal display, a transflective liquid crystal display, a reflectiveliquid crystal display, a direct-view liquid crystal display, and aprojection liquid crystal display). An example of a display device usingelectronic ink, Electronic Liquid Powder (registered trademark), orelectrophoretic elements is electronic paper. In a transflective liquidcrystal display or a reflective liquid crystal display, some or all ofpixel electrodes function as reflective electrodes. For example, some orall of pixel electrodes are formed to contain aluminum, silver, or thelike. In such a case, a memory circuit such as SRAM can be providedunder the reflective electrodes, leading to lower power consumption.

For example, in this specification and the like, it is possible toemploy an active matrix method in which an active element (a non-linearelement) is included in a pixel or a passive matrix method in which anactive element is not included in a pixel.

In the active matrix method, not only a transistor but also a variety ofactive elements, for example, a metal insulator metal (MIM) or a thinfilm diode (TFD) can be used. These elements are fabricated with a smallnumber of steps, resulting in low manufacturing cost or high yield.Furthermore, since these elements are small, the aperture ratio can beincreased, leading to low power consumption and high luminance.

Since an active element is not used in the passive matrix method, thenumber of manufacturing steps is small, so that the manufacturing costcan be reduced or the yield can be increased. Furthermore, since anactive element is not used, the aperture ratio can be improved, leadingto low power consumption or high luminance.

Note that the light-emitting device of one embodiment of the presentinvention may be used not only as a display device but also as alighting device. By using the light-emitting device as a lightingdevice, it can be used for interior lighting having an attractive designor as lighting from which light radiates in various directions.Alternatively, the light-emitting device may be used as a light sourcesuch as a backlight or a front light, that is, a lighting device for adisplay panel.

As described above, in one embodiment of the present invention,providing the light-emitting element with an auxiliary electrodesuppresses a voltage drop of the electrode and reduces unevenness indisplay luminance of the light-emitting device.

In the light-emitting device of one embodiment of the present invention,a conductive film having high wettability to the material of a bondinglayer is provided in contact with the bonding layer. Therefore, entry ofair bubbles can be prevented when a pair of substrates are attached toeach other with the bonding layer, so that the substrates can beattached with a high yield.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 2

In this embodiment, an input/output device of one embodiment of thepresent invention will be described with reference to a drawing.

Although this embodiment shows an example in which an organic EL elementis used as a light-emitting element, an input/output device of oneembodiment of the present invention is not limited to this and mayinclude another light-emitting element or a display element.

This embodiment shows an example in which a capacitive touch sensor isused as a sensor; however, an input/output device of one embodiment ofthe present invention is not limited to this, and a sensing elementincluded in the sensor is not limited to a capacitor. Moreover, anotherinput device may be used.

Examples of a capacitive touch sensor are a surface capacitive touchsensor and a projected capacitive touch sensor. Examples of a projectedcapacitive touch sensor are a self-capacitive touch sensor and a mutualcapacitive touch sensor. The use of a mutual capacitive type ispreferable because multiple points can be sensed simultaneously.Alternatively, a resistive touch sensor, an ultrasonic touch sensor, oran optical touch sensor may be used.

As illustrated in FIGS. 5A and 5B, an input device is attached to thelight-emitting device of one embodiment of the present invention, whichis shown in Embodiment 1, whereby an input/output device of oneembodiment of the present invention can be fabricated.

Light-emitting devices illustrated in FIGS. 5A and 5B each include thebonding layer 811, the insulating layer 813, the transistor 820, thelight-emitting element 830, the conductive layer 851, the insulatinglayer 852, the conductive layer 853, the bonding layer 841, and the likebetween the substrate 801 and the substrate 803. Specific Example 3 ofCross-sectional Structure (FIG. 3A) in Embodiment 1 can be referred tofor a specific structure of the light-emitting devices. Note that thelight-emitting devices of FIGS. 5A and 5B differ from that of FIG. 3A innot including the overcoat 849.

In input devices illustrated in FIGS. 5A and 5B, a substrate 899 and aninsulating layer 897 are attached to each other with a bonding layer898, and a capacitor 880 is provided over the insulating layer 897 as asensing element. The capacitor 880 includes a plurality of conductivelayers 896, a conductive layer 894 connected to the conductive layers896, and an insulating layer 895 between the conductive layers 896 andthe conductive layer 894. The conductive layers 896 are electricallyconnected to each other through the conductive layer 894. The capacitor880 may be covered with an insulating layer 893. The conductive layer896 is electrically connected to an FPC 891 through a connector 892.

FIG. 5A illustrates an example where the insulating layer 893 isattached to the substrate 803 with a bonding layer 889 placedtherebetween. In this manner, the input/output device may include threesubstrates 801, 803, and 899.

FIG. 5B illustrates an example where the insulating layer 893 isattached to a substrate 888 with the bonding layer 889 placedtherebetween, and the substrate 899 is attached to the substrate 803with a bonding layer 879 placed therebetween. In this manner, theinput/output device may include four substrates 801, 803, 888, and 899.

As materials used for the input device, it is possible to use materialsfor the substrate, insulating layer, bonding layer, conductive layer,connector, and the like of the light-emitting device in Embodiment 1.Note that layers overlapping a light-emitting region of thelight-emitting element (here, the substrate 899, the bonding layer 898,the insulating layer 897, the conductive layer 896, the insulating layer895, the insulating layer 893, the bonding layer 889, the substrate 888,and the bonding layer 879) are formed using a material that transmitslight from the light-emitting element. A layer that does not overlap thelight-emitting region of the light-emitting element (e.g., theconductive layer 894) does not necessarily have transmittance.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 3

In this embodiment, an input/output device of one embodiment of thepresent invention will be described with reference to drawings.

Although this embodiment shows an example in which an organic EL elementis used in a display portion, an input/output device of one embodimentof the present invention is not limited to this and may include anotherlight-emitting element or a display element in a display portion.

This embodiment shows an example where an input device is a touch sensorincluding a sensing element (e.g., a capacitor) and an active electrode(e.g., a transistor) in each sensing unit (such a touch sensor is alsoreferred to as an active matrix touch sensor). In this embodiment, acapacitor is used as a sensing element as an example; however, aninput/output device of one embodiment of the present invention is notlimited to this and may include another sensing element such as alight-receiving element or another input device.

The input/output device of one embodiment of the present inventionincludes an active matrix touch sensor and a display element between apair of substrates. The touch sensor included in the input/output deviceof one embodiment of the present invention is a capacitive touch sensor,for example.

In the input/output device including a sensor portion and a displayportion that overlap with each other, parasitic capacitance is sometimesgenerated between a wiring or an electrode included in the capacitivetouch sensor and a wiring or an electrode included in the displayportion. The parasitic capacitance might cause a capacitance change tobe decreased when a finger or the like approaches the touch sensor,resulting in a decrease in the detection sensitivity of the touchsensor. The detection sensitivity of the touch sensor might be decreasedalso when noise generated while the display element operates travels tothe touch sensor through the parasitic capacitance.

By sufficiently increasing the distance between the sensor portion andthe display portion, the adverse effect of the parasitic capacitance andthe noise can be avoided and the decrease in the detection sensitivityof the touch sensor can be suppressed; however, the thickness of thewhole input/output device is increased in some cases.

In the input/output device of one embodiment of the present invention,an active matrix touch sensor is used. The touch sensor includes atransistor and a capacitor. The transistor and the capacitor areelectrically connected to each other.

In the active matrix touch sensor, an electrode of the capacitor and aread wiring can be formed in different layers. When the read wiring hasa narrow width, parasitic capacitance can be small. Accordingly, adecrease in the detection sensitivity of the touch sensor can besuppressed.

Furthermore, generation of parasitic capacitance might decrease theamplitude of a detection signal and decrease the detection sensitivity.In one embodiment of the present invention, a detection signal isamplified and the amplified signal is output; thus, the adverse effectof the parasitic capacitance can be suppressed.

In one embodiment of the present invention, the use of an active matrixtouch sensor can reduce the distance between the sensor portion and thedisplay portion and thin the input/output device. Moreover, the touchsensor and the display element can be located between two substrates,whereby the input/output device can have a small thickness. Here, theuse of the active matrix touch sensor can suppress a decrease in thedetection sensitivity of the touch sensor even when the distance betweenthe sensor portion and the display portion is reduced. Therefore, in oneembodiment of the present invention, both thinness and high detectionsensitivity of the touch sensor or the input/output device can beachieved. Furthermore, by using a flexible material for the pair ofsubstrates, the input/output device can have flexibility. In addition,one embodiment of the present invention can provide an input/outputdevice with high resistance to repeated bending or a large-sizeinput/output device.

In the touch sensor included in the input/output device of oneembodiment of the present invention, an oxide conductor layer may beused for the electrode of the capacitor. In the active matrix touchsensor, a semiconductor layer and a conductive film of the transistorand the electrode of the capacitor are preferably formed in the samestep. Thus, the number of steps for fabricating the input/output devicecan be reduced, and the fabrication cost can be reduced.

When the oxide conductor layer is used as the electrode of thecapacitor, the input/output device of one embodiment of the presentinvention sometimes has smaller viewing angle dependence and a higherNTSC ratio than an input/output device using another material as acapacitor electrode.

Specifically, one embodiment of the present invention is an input/outputdevice including a touch sensor, a light-blocking layer, and a displayelement between a pair of electrodes. The light-blocking layer islocated between the touch sensor and the display element and includes aportion overlapping with a transistor included in the touch sensor. Thedisplay element includes a portion overlapping with a capacitor includedin the touch sensor.

The display element can be, but is not particularly limited to, anorganic EL element. Therefore, in the above structure, the displayelement may include a first electrode, a second electrode, and a layercontaining a light-emitting organic compound. An insulating filmcovering an end portion of the first electrode may be provided. Thelayer containing a light-emitting organic compound may be locatedbetween the first electrode and the second electrode. The insulatingfilm may include a portion overlapping with the transistor included inthe touch sensor.

<Structure Example of Input/output Device>

FIGS. 6A and 6B are projection views illustrating a structure of aninput/output device of one embodiment of the present invention.

FIG. 6A is a projection view of an input/output device 500 of oneembodiment of the present invention. FIG. 6B is a projection viewillustrating a structure of a sensing unit 10U included in theinput/output device 500.

The input/output device 500 described in this embodiment includes aninput portion 100 and a display portion 501.

The input portion 100 has flexibility. The input portion 100 includes ascan line G1, a signal line DL, a flexible substrate 16, and a pluralityof sensing units 10U. The sensing unit 10U shown in FIG. 6B is providedwith window portions 14 that transmit visible light. The sensing units10U are arranged in a matrix. The scan line G1 is electrically connectedto a plurality of sensing units 10U located in the row direction(indicated by the arrow R in the drawing). The signal line DL iselectrically connected to a plurality of sensing units 10U located inthe column direction (indicated by the arrow C in the drawing). Theflexible substrate 16 supports the sensing units 10U, the scan line G1,and the signal line DL.

The display portion 501 includes a flexible substrate 510 and aplurality of pixels 502. The plurality of pixels 502 overlap with thewindow portion 14 and are arranged in a matrix. The flexible substrate510 supports the plurality of pixels 502 (FIGS. 6A and 6B).

The sensing unit 10U includes a sensing element C overlapping with thewindow portion 14 and a sensing circuit 19 electrically connected to thesensing element C (FIG. 6B).

In the sensing element C, an insulating layer is provided between a pairof electrodes that are a first electrode 11 and a second electrode 12 inthis embodiment.

The sensing circuit 19 receives a selection signal and supplies asensing signal DATA based on the change in the capacitance of thesensing element C or parasitic capacitance.

The scan line G1 can supply the selection signal. The signal line DL cansupply the sensing signal DATA. The sensing circuit 19 is located tooverlap with a gap between the window portions 14.

In addition, the input/output device 500 described in this embodimentincludes a coloring layer between the sensing unit 10U and the pixel 502overlapping with the window portion 14 of the sensing unit 10U.

The input/output device 500 in this embodiment includes the flexibleinput portion 100 including the plurality of sensing units 10U eachhaving the window portions 14 transmitting visible light, and theflexible display portion 501 including the plurality of pixels 502overlapping with the window portions 14. The coloring layer is includedbetween the window portion 14 and the pixel 502.

With such a structure, the input/output device can supply a sensingsignal based on the change in the capacitance or the parasiticcapacitance and positional information of the sensing unit supplying thesensing signal, can display image data relating to the positionalinformation of the sensing unit, and can be bent. As a result, a novelinput/output device with high convenience or high reliability can beprovided.

The input/output device 500 may include a flexible substrate FPC1(hereinafter simply referred to as FPC1) supplied with a signal from theinput portion 100 and/or a flexible substrate FPC2 (hereinafter simplyreferred to as FPC2) supplying a signal including image data to thedisplay portion 501.

The input/output device 500 may be provided with a protective layer 17 pthat protects the input/output device 500 from scratches and/or anantireflective layer 567 p that reduces the intensity of external lightthe input/output device 500 reflects.

The input/output device 500 also includes a scan line driver circuit 503g that supplies a selection signal to a scan line of the display portion501 and a terminal 519 electrically connected to FPC2 and a wiring 511that supplies a signal.

Individual components included in the input/output device 500 will bedescribed below. Note that these components cannot be clearlydistinguished, and one component also serves as another component orincludes part of another component in some cases.

For example, the input portion 100 provided with coloring layersoverlapping with the window portions 14 also serves as a color filter.

Furthermore, for example, the input/output device 500 in which the inputportion 100 overlaps the display portion 501 serves as the displayportion 501 as well as the input portion 100.

The input portion 100 includes a plurality of sensing units 10U and theflexible substrate 16 supporting the sensing units 10U. For example, theplurality of sensing units 10U are arranged in a matrix over theflexible substrate 16.

The window portion 14 transmits visible light.

For example, the window portion 14 may be formed by overlapping theflexible substrate 16, the sensing element C, and a flexible protectivebase material 17 so as not to prevent transmission of visible light.

For instance, an opening may be provided in a material that does nottransmit visible light. Specifically, one or a plurality of openingshaving any of a variety of shapes such as a rectangle may be provided.

Coloring layers that transmit light of a predetermined color areprovided so as to overlap with the window portions 14. For example, acoloring layer CFB transmitting blue light, a coloring layer CFGtransmitting green light, and a coloring layer CFR transmitting redlight are provided (FIG. 6B).

In addition to the coloring layers transmitting blue light, green light,and/or red light, coloring layers transmitting light of various colorssuch as white and yellow can be provided.

A light-blocking layer BM is provided to surround the window portions14. The light-blocking layer BM is less likely to transmit light thanthe window portion 14. Note that in this specification and the like, ablack matrix is used as the light-blocking layer, and the letter symbolBM is used to denote the light-blocking layer.

The scan line G1, the signal line DL, a wiring VPI, a wiring RES, awiring VRES, and the sensing circuit 19 can be provided to overlap withthe light-blocking layer BM.

Note that a light-transmitting overcoat covering the coloring layers andthe light-blocking layer BM can be provided.

The flexible protective base material 17 and/or the protective layer 17p can be provided. The flexible protective base material 17 and/or theprotective layer 17 p protects) the input portion 100 by preventingdamage.

For example, a resin film, a resin plate, or a stack of polyester,polyolefin, polyamide, polyimide, polycarbonate, or an acrylic resin canbe used as the protective base material 17.

For example, a hard coat layer or a ceramic coat layer can be used asthe protective layer 17 p. Specifically, a layer containing a UV curableresin or aluminum oxide may be formed to overlap with the secondelectrode.

The display portion 501 includes a plurality of pixels 502 arranged in amatrix (see FIG. 6B).

For example, the pixel 502 includes a sub-pixel 502B, a sub-pixel 502G,and a sub-pixel 502R, and each sub-pixel includes a display element anda pixel circuit for driving the display element.

Note that the sub-pixel 502B in the pixel 502 is positioned so as tooverlap with the coloring layer CFB, the sub-pixel 502G is positioned soas to overlap with the coloring layer CFG, and the sub-pixel 502R ispositioned so as to overlap with the coloring layer CFR.

In this embodiment, an example of using an organic EL element that emitswhite light as a display element is described; however, the displayelement is not limited to such an element and can be the light-emittingelement or the display element exemplified in Embodiment 1.

The display portion 501 includes the wirings 511 through which signalscan be supplied. The wirings 511 are provided with the terminal 519.Note that FPC2 through which signals such as an image signal and asynchronization signal can be supplied is electrically connected to theterminal 519.

Note that a printed wiring board (PWB) may be attached to FPC2.

The sensing element C includes the first electrode 11, the secondelectrode 12, and an insulating layer between the first electrode 11 andthe second electrode 12.

The first electrode 11 is formed apart from other regions, for example,is formed into an island shape. Preferably, a layer that can be formedin the same step as that of the first electrode 11 is placed close tothe first electrode 11 so that the user of the input/output device 500does not recognize the first electrode 11. More preferably, the numberof window portions 14 provided in the gap between the first electrode 11and the layer placed close to the first electrode 11 is reduced as muchas possible. It is particularly preferred that the window portions 14not be provided in the gap.

The second electrode 12 is provided to overlap with the first electrode11, and the insulating layer is provided between the first electrode 11and the second electrode 12.

For example, when an object whose dielectric constant is different fromthat of the air gets closer to the first electrode 11 or the secondelectrode 12 of the sensing element C in the air, capacitance is formedand serves as parasitic capacitance of a circuit. Specifically, when afinger or the like gets closer to one electrode of the sensing elementC, capacitance is formed between the one electrode and the finger or thelike. Then, the formed capacitance serves as parasitic capacitance of acircuit that is electrically connected to the sensing element C, and theoperation of the sensing circuit is changed. Accordingly, the sensingelement C can be used in a proximity sensor.

For example, the capacitance of the sensing element C that can changeits form varies with the change in the form of the sensing element C.

Specifically, when a finger or the like is in contact with the sensingelement C and the gap between the first electrode 11 and the secondelectrode 12 becomes small, the capacitance of the sensing element Cincreases. Accordingly, the sensing element C can be used in a tactilesensor and thus can sense writing pressure, for instance.

Specifically, when the sensing element C is folded, the gap between thefirst electrode 11 and the second electrode 12 becomes small; thus, thecapacitance of the sensing element C increases. Accordingly, the sensingelement C can be used in a bend sensor.

The first electrode 11 and the second electrode 12 contain a conductivematerial.

The first electrode 11 and the second electrode 12 can be formed usingan inorganic conductive material, an organic conductive material, metal,or conductive ceramics, for example.

Specifically, it is possible to use a metal element selected fromaluminum, chromium, copper, tantalum, titanium, molybdenum, tungsten,nickel, silver, and manganese; an alloy containing any of the metalelements; an alloy containing any of the metal elements in combination;or the like.

Alternatively, it is possible to use conductive oxide such as indiumoxide, indium tin oxide, indium zinc oxide, zinc oxide, or zinc oxide towhich gallium is added.

Alternatively, graphene or graphite can be used. A film containinggraphene can be formed, for example, by reducing a film containinggraphene oxide. Examples of a reducing method are a method using heatand a method using a reducing agent.

Alternatively, a conductive polymer can be used.

The sensing circuit 19 includes transistors. Moreover, the sensingcircuit 19 may include wirings that supply a power supply potential anda signal, such as the signal line DL, the wiring VPI, a wiring CS, thescan line G1, the wiring RES, and the wiring VRES.

Note that the sensing circuit 19 may be provided so as not to overlapwith the window portions 14. For example, when a wiring is located notto overlap with the window portion 14, one side of the sensing unit 10Ucan be visually recognized easily from the other side of the sensingunit 10U.

A variety of circuits that can convert the sensing signal DATA suppliedfrom the sensing unit 10U and supply the converted signal to FPC1 can beused as a converter CONV (FIG. 6A).

<Structure Example of Input Portion>

FIGS. 7A, 7B, 7C1, and 7C2 are diagrams for explaining a structure ofthe input portion 100 in one embodiment of the present invention.

FIG. 7A is a block diagram illustrating the structure of the inputportion 100 in one embodiment of the present invention. FIG. 7B is acircuit diagram illustrating configurations of the converter CONV andthe sensing unit 10U. FIGS. 7C1 and 7C2 are timing charts for explaininga method for driving the sensing unit 10U. FIG. 8A is a circuit diagramillustrating the sensing units 10U arranged in a matrix.

The input portion 100 described in this embodiment includes a pluralityof sensing units 10U arranged in a matrix, scan lines G1 electricallyconnected to sensing units 10U arranged in the row direction, signallines DL electrically connected to sensing units 10U arranged in thecolumn direction, and the flexible substrate 16 provided with thesensing units 10U, the scan lines G1, and the signal lines DL (FIG. 7A).

For example, the plurality of sensing units 10U can be arranged in amatrix of n rows and m columns (n and m are each a natural number of 1or more).

The sensing unit 10U includes the sensing element C having the secondelectrode 12 electrically connected to the wiring CS; thus, thepotential of the second electrode 12 of the sensing element C can becontrolled using a control signal supplied through the wiring CS.

The sensing unit 10U includes a first transistor M1 in which a gate iselectrically connected to the first electrode 11 of the sensing elementC and a first electrode is electrically connected to the wiring VPI(FIG. 7B). The wiring VPI can supply a ground potential, for example.

The sensing unit 10U may include a second transistor M2 in which a gateis electrically connected to the scan line G1, a first electrode iselectrically connected to a second electrode of the first transistor M1,and a second electrode is electrically connected to the signal line DL.The scan line G1 can supply a selection signal. The signal line DL cansupply the sensing signal DATA, for example.

The sensing unit 10U may include a third transistor M3 in which a gateis electrically connected to the wiring RES, a first electrode iselectrically connected to the first electrode 11 of the sensing elementC, and a second electrode is electrically connected to the wiring VRES.The wiring RES can supply a reset signal. The wiring VRES can supply,for example, a potential capable of turning on the first transistor M1.

The capacitance of the sensing element C is changed when an object comesclose to the first electrode 11 or the second electrode 12 or when thedistance between the first electrode 11 and the second electrode 12 ischanged, for example. Thus, the sensing unit 10U can supply the sensingsignal DATA based on a change in the capacitance of the sensing elementC or parasitic capacitance.

The sensing unit 10U includes the wiring CS that can supply a controlsignal capable of controlling the potential of the second electrode 12of the sensing element C. Note that the second electrode 12 may alsoserve as the wiring CS of the sensing circuit.

A node where the first electrode 11 of the sensing element C, the gateof the first transistor M1, and the first electrode of the thirdtransistor M3 are electrically connected is referred to as a node A.

The wiring VRES can supply a predetermined potential. For example, thewiring VRES can provide the gate of the transistor included in thesensing unit 10U with a potential for turning on the transistor. Thewiring VPI can supply a ground potential, for example. A wiring VPO anda wiring BR can supply, for example, a high power supply potentialsufficient to turn on a transistor.

The wiring RES can supply a reset signal. The scan line G1 can supply aselection signal. The wiring CS can supply a control signal forcontrolling the potential of the second electrode 12 of the sensingelement C.

The signal line DL can supply the sensing signal DATA. A terminal OUTcan supply a signal obtained by conversion based on the sensing signalDATA.

A driver circuit GD can supply a selection signal at given timings, forexample. The converter CONY has a conversion circuit. A variety ofcircuits that can convert the sensing signal DATA and supply theresulting signal to the terminal OUT can be used for the converter CONV.For example, a source follower circuit or a current mirror circuit maybe configured by electrically connecting the converter CONV to thesensing unit 10U.

Specifically, a source follower circuit can be configured with theconverter CONV using a transistor M4 (FIG. 7B). Note that the transistorM4 may be a transistor that can be fabricated in the same steps as thefirst to third transistors M1 to M3.

As described above, in the active matrix touch sensor of one embodimentof the present invention, the electrode of the sensing element and theread wiring can be formed in different layers. As shown in FIG. 8B, thefirst electrode 11 and the signal line DL are formed in different layersand the width of the signal line DL is made small, whereby parasiticcapacitance can be reduced. Consequently, a decrease in the detectionsensitivity of the touch sensor can be suppressed. Here, an example isshown in which the first electrode 11 overlaps with a plurality ofpixels 502 shown in an enlarged view of FIG. 8C. The second electrode 12that serves as the other electrode of the capacitor (the sensing elementC) and is not shown in FIG. 8B has a potential equal to that of thewiring CS (or the second electrode 12 corresponds to the wiring CS).

<Example of Method for Driving Input Portion>

A method for driving the input portion will be described.

<<First Step>>

In a first step, a reset signal for turning on the third transistor M3and subsequently turning off the third transistor M3 is supplied to thegate of the third transistor M3, and a potential of the first electrode11 of the sensing element C is set at a predetermined potential (seePeriod T1 in FIG. 7C1).

Specifically, a reset signal is supplied from the wiring RES. The thirdtransistor M3 supplied with the reset signal makes the node A have apotential capable of turning on the first transistor M1, for example(FIG. 7B).

<<Second Step>>

In a second step, a selection signal for turning on the secondtransistor M2 is supplied to the gate of the second transistor M2, andthe second electrode of the first transistor M1 is made electricallyconnected to the signal line DL.

Specifically, a selection signal is supplied from the scan line G1. Thesecond transistor M2 supplied with the selection signal electricallyconnects the second electrode of the first transistor M1 to the signalline DL (see Period T2 in FIG. 7C1).

<<Third Step>>

In a third step, a control signal is supplied to the second electrode 12of the sensing element C, and a potential that varies depending on thecontrol signal and the capacitance of the sensing element C is suppliedto the gate of the first transistor M1.

Specifically, a rectangular control signal is supplied from the wiringCS. With supply of the rectangular control signal to the secondelectrode 12, the potential of the node A rises depending on thecapacitance of the sensing element C (see the latter half of Period T2in FIG. 7C1).

For example, when the sensing element C is placed in the air and anobject with a higher dielectric constant than the air comes close to thesecond electrode 12 of the sensing element C, the apparent capacitanceof the sensing element C increases.

Consequently, a change in the potential of the node A due to arectangular control signal is smaller than that when an object with ahigher dielectric constant than the air is not placed close to the firstelectrode of the sensing element C (see a solid line in FIG. 7C2).

<<Fourth Step>>

In a fourth step, a signal based on a change in the gate potential ofthe first transistor M1 is supplied to the signal line DL.

For example, a current that is changed on the basis of a change in thegate potential of the first transistor M1 is supplied to the signal lineDL.

The converter CONV converts a change in current flowing through thesignal line DL into a change in voltage and outputs the voltage.

<<Fifth Step>>

In a fifth step, a selection signal for turning off the secondtransistor M2 is supplied to the gate of the second transistor M2.

The first to fifth steps are repeated for every row of the scan linesG1(1) to G1(n).

<Specific Example of Conductive Layer 853 in Input/output Device>

In one embodiment of the present invention, a first electrode, an ELlayer, and a second electrode are formed in this order over a firstsubstrate, and an active matrix touch sensor (e.g., a sensing elementand a sensing circuit) is formed over a second substrate. Moreover, asecond conductive layer (the conductive layer 853), an insulating layer,and a first conductive layer (the conductive layer 851) are formed inthis order over the second substrate. In this structure, the firstconductive layer and the second conductive layer are electricallyconnected to each other through an opening in the insulating layer.Moreover, the first substrate and the second substrate face each otherso that the second electrode and the first conductive layer areconnected to each other. Thus, the first conductive layer, the secondconductive layer, and the second electrode can be electrically connectedto each other.

In this manner, the conductive layer formed on the second substrate sideis electrically connected to the second electrode of the light-emittingelement formed over the first substrate, whereby the conductive layercan increase the conductivity of the second electrode. This structurecan suppress a potential drop due to the resistance of the secondelectrode and suppress unevenness in display luminance even in aninput/output device including a large-area display portion or aninput/output device including a top-emission light-emitting unit.Moreover, the auxiliary electrode protects the light-emitting elementfrom damage, so that the input/output device can have high reliability.

In the above structure, at least one of the first conductive layer andthe second conductive layer is preferably formed using the same materialand the same step as those of at least one conductive layer (e.g., awiring or an electrode of the transistor or the sensing element)included in the active matrix touch sensor (specifically, the inputportion 100, for example). Similarly, the insulating layer placedbetween the first and second conductive layers is preferably formedusing the same material and the same step as those of at least oneinsulating layer included in the active matrix touch sensor.Accordingly, an auxiliary wiring of the light-emitting element can beformed without an increase in the number of steps. For the details ofthe first and second conductive layers, the description of Embodiment 1can also be referred to.

For example, as illustrated in FIGS. 9A and 9B, at least one conductivelayer 853 can be formed using the same material and the same step asthose of the signal line DL. Note that transistors are not shown inFIGS. 9A and 9B. For instance, a source electrode and a drain electrodeof a transistor can be formed using the same material and the same stepas those of the signal line DL. For another instance, a gate electrodeof the transistor can be formed using the same material and the samestep as those of the scan line G1, the wiring VPI, the wiring RES, andthe wiring VRES.

When the conductive layer 853 is electrically insulated from the firstelectrode 11 of the sensing element C with an insulating layer placedtherebetween, the conductive layer 853 may be provided to overlap withthe sensing element C. In this case, it is preferred that the conductivelayer 853 not overlap with a display region of a pixel.

FIG. 9C is an enlarged view of a region indicated by a dashed-dottedline in FIG. 9B. FIG. 9D is a cross-sectional view along dashed-dottedline X1-Y1 in FIG. 9C.

As illustrated in FIGS. 9B to 9D, a conductive layer 853 a and aconductive layer 853 b that are separated by the signal line DL may beelectrically connected to each other through a conductive layer 304 a.At least one conductive layer 304 a can be formed using the samematerial and the same step as those of the scan line G1, the wiring VPI,the wiring RES, and the wiring VRES.

In the cross-sectional view in FIG. 9D, the substrate 803, the bondinglayer 841, the insulating layer 843, and the conductive layer 304 a arestacked in this order. The conductive layer 304 a is electricallyconnected to the conductive layers 853 a and 853 b in an opening in agate insulating layer 305. The conductive layers 853 a and 853 b areelectrically insulated from a signal line DL(j) by the gate insulatinglayer 305 and/or an insulating layer 312. The insulating layer 312, aninsulating layer 314, an insulating layer 852 a, the second electrode12, an insulating layer 852 b, the light-blocking layer 847, and theconductive layer 851 are stacked in this order over the signal lineDL(j) and the conductive layers 853 a and 853 b. A structure of acontact portion for connecting the conductive layer 851 and theconductive layers 853 a and 853 b will be described below.

As illustrated in FIG. 10A, it is possible to provide at least oneconductive layer 853 a formed using the same material and the same stepas those of the signal line DL, and at least one conductive layer 853 bformed using the same material and the same step as those of the scanline G1, the wiring VPI, the wiring RES, and the wiring VRES. Note thattransistors are not shown in FIG. 10A. The conductive layers 853 a and853 b electrically connected to each other have a function similar tothat of the conductive layer 853.

FIG. 10B is a cross-sectional view along dashed-dotted line X2-Y2 inFIG. 10A.

In the cross-sectional view in FIG. 10B, the substrate 803, the bondinglayer 841, the insulating layer 843, and the conductive layer 853 b arestacked in this order. The conductive layer 853 b is electricallyconnected to the conductive layer 853 a in an opening in the gateinsulating layer 305. The insulating layer 312, the insulating layer314, the first electrode 11, the insulating layer 852 a, the secondelectrode 12, the insulating layer 852 b, the light-blocking layer 847,and the conductive layer 851 are stacked in this order over theconductive layer 853 a.

A structure in FIG. 10C where the conductive layer 853 does not overlapwith the first electrode 11 of the sensing element C is anotherembodiment of the present invention. In this structure, there is noparticular limitation on the vertical positional relation between theconductive layer 853 and the first electrode 11 in the directionperpendicular to the top face of the top view in FIG. 10C. Note thattransistors are not shown in FIG. 10C.

<Specific Example 1 of Cross-sectional Structure of Input/output Device>

FIG. 11A is an example of a cross-sectional view of the input/outputdevice of one embodiment of the present invention. FIG. 11B is anenlarged view of a transistor FET1 and a sensing element C1.

The input/output device in FIG. 11A includes the substrate 801, thebonding layer 811, the insulating layer 813, a plurality of transistors,a conductive layer 857 a, the insulating layer 815, the insulating layer817 a, the insulating layer 817 b, the conductive layer 856, a pluralityof light-emitting elements, the insulating layer 821, the bonding layer822, the spacer 823, the conductive layer 851, the insulating layer 852a, the insulating layer 852 b, the conductive layer 853, a conductivelayer 854, the coloring layer 845, the light-blocking layer 847, aconductive layer 857 b, a conductive layer 857 c, a plurality of sensingelements, the insulating layer 843, the bonding layer 841, and thesubstrate 803. The bonding layer 822, the conductive layer 851, theinsulating layer 852 a, the insulating layer 852 b, the insulating layer843, the bonding layer 841, and the substrate 803 transmit visiblelight.

In FIG. 11A, the light-emitting element 830, the transistors, and thesensing element C1 included in the light-emitting unit 804 and thedriver circuit unit 806 are sealed with the substrate 801, the substrate803, and the bonding layer 822.

To fabricate the input/output device in FIG. 11A, first, a pair offormation substrates is prepared. The insulating layer 813, thetransistor 820, the light-emitting element 830, and the like are formedover one of the formation substrates. The insulating layer 843, thetransistor FET1, the sensing element C1, the conductive layer 851, theinsulating layer 852 a, the insulating layer 852 b, the conductive layer853, and the like are formed over the other formation substrate.Subsequently, the formation substrates are attached to each other withthe bonding layer 822. Then, the formation substrates are peeled, thesubstrate 801 is attached to the exposed insulating layer 813 with thebonding layer 811, and similarly, the substrate 803 is attached to theexposed insulating layer 843 with the bonding layer 841. Thus, theinput/output device is completed.

The input/output device of one embodiment of the present invention canbe fabricated by applying a method for manufacturing a light-emittingdevice of one embodiment of the present invention (specifically, bychanging a structure of a layer to be separated); the manufacturingmethod will be described in detail in Embodiment 5. A transistor and thelike are formed over a formation substrate with high heat resistance, sothat a highly reliable transistor and an insulating film withsufficiently high moisture resistance can be formed at hightemperatures. Then, the transistor and the insulating film aretransferred to a substrate with low heat resistance, whereby a highlyreliable input/output device can be manufactured. Thus, one embodimentof the present invention can provide a thin or/and lightweightinput/output device with high reliability.

The conductive layer 851 is connected to the conductive layer 854through an opening in the insulating layer 852 b. The conductive layer854 is connected to the conductive layer 853 through an opening in theinsulating layer 852 a. The conductive layer 851 is also connected tothe second electrode 835. That is, the second electrode 835, theconductive layer 851, the conductive layer 854, and the conductive layer853 are electrically connected to each other, thereby suppressing avoltage drop of the second electrode 835 and thus reducing unevenness indisplay luminance of the input/output device. Note that the insulatinglayer 852 b is not always necessary.

Furthermore, the conductive layer 851 and the conductive layer 853 maybe directly connected without providing the conductive layer 854. Anovercoat may be provided between the conductive layer 851 and thecoloring layer 845 or the light-blocking layer 847.

Since the conductive layer 851 is formed using a material that transmitlight from the light-emitting element 830, the conductive layer 851 canbe formed extensively on the whole surface of the input/output device.Accordingly, the area where the second electrode 835 and the conductivelayer 851 are in contact with each other can be increased, and thecontact resistance between the second electrode 835 and the conductivelayer 851 can be lowered.

The conductive layer 853 does not necessarily have transmittance becauseit does not overlap a light-emitting region of the light-emittingelement 830 (i.e., it overlaps the insulating layer 821). For thisreason, the conductive layer 853 can be formed using a wider range ofmaterials than the conductive layer 851. When the conductive layer 853is formed using a material with lower resistance than the conductivelayer 851, a voltage drop of the second electrode 835 can be furthersuppressed. Thus, one embodiment of the present invention achieves aninput/output device with little unevenness in display luminance.

The substrate 801 and the substrate 803 are attached to each other withthe bonding layer 822. The bonding layer 822 is positioned between thelight-emitting element 830 and the conductive layer 851. In this case,the wettability of the conductive layer 851 to a material of the bondinglayer 822 is preferably high. High wettability to the material of thebonding layer 822 can reduce air bubbles entering when the pair offormation substrates are attached to each other, and the substrates canbe attached with a high yield. Moreover, the input/output device can behighly reliable. The conductive layer 851 may be provided only in thelight-emitting unit 804, provided in the light-emitting unit 804 and thedriver circuit unit 806, or provided on the entire surface over theinsulating layer 843.

The conductive layer 857 a is electrically connected to an externalinput terminal through which a signal or a potential from the outside istransmitted to the driver circuit unit 806. Here, an example in whichFPC2 is provided as the external input terminal is described. To preventan increase in the number of fabrication steps, the conductive layer 857a is preferably formed using the same material and the same step asthose of the electrode or the wiring in the light-emitting unit or thedriver circuit unit. Here, an example is described in which theconductive layer 857 a is formed using the same material and the samestep as those of the electrodes of the transistor 820. The conductivelayer 857 a is electrically connected to FPC2 through a connector 825 a.Similarly, the conductive layers 857 b and 857 c are electricallyconnected to FPC1 through a connector 825 b.

As illustrated in FIG. 11B, the transistor FET1 includes a gateelectrode 304 over the insulating layer 843, the gate insulating layer305 covering the gate electrode 304, and a semiconductor layer 308 a anda pair of electrodes (an electrode 310 a and an electrode 310 b) overthe gate insulating layer 305. The semiconductor layer 308 a isconnected to the pair of electrodes. The pair of electrodes functions asa source electrode and a drain electrode. The transistor FET1 is coveredwith the insulating layer 312 and the insulating layer 314. One of theinsulating layers 312 and 314 is not necessarily provided. The sensingelement C1 includes the first electrode 11 over the insulating layer314, the insulating layer 852 a over the first electrode 11, and thesecond electrode 12 over the insulating layer 852 a. The insulatinglayer 852 b is provided over the second electrode 12. The light-blockinglayer 847 and the coloring layer 845 are provided over insulating layer852 b. Although an example where the transistor FET1 overlaps with thelight-blocking layer 847 and the sensing element C1 overlaps with thecoloring layer 845 is shown here, one embodiment of the presentinvention is not limited to this example. For example, both thetransistor FET1 and the sensing element C1 may overlap with thelight-blocking layer 847. Here, the electrode of the sensing element C1does not necessarily have transmittance. When the electrode of thesensing element C1 overlaps with the coloring layer 845 or alight-emitting region of the light-emitting element 830, the electrodeis preferably formed using a light-transmitting material.

The first electrode 11 or the second electrode 12 may be formed usingthe same material and the same step as those of a backgate of atransistor. FIG. 11A illustrates an example where a transistor includedin the driver circuit unit 806 has a backgate; however, one embodimentof the present invention is not limited to this example.

Note that a user of the input/output device in FIG. 11A may recognize awiring, the electrode of the transistor FET1, the conductive layer 853,or the like. For this reason, a film with low reflectivity or alight-blocking film may be provided between the substrate 803 and thetransistor FET1. Moreover, a conductive film with low reflectivity maybe used as the conductive layer 853.

<Specific Example 2 of Cross-sectional Structure of Input/output Device>

FIG. 12A is an example of a cross-sectional view of the input/outputdevice of one embodiment of the present invention. FIG. 12B is anenlarged view of a transistor FET2 and a sensing element C2.

The input/output device in FIG. 12A is different from that in FIG. 11Ain including the transistor FET2 and the sensing element C2. Thedescription of features common to the input/output device of FIG. 11A isomitted.

As illustrated in FIG. 12B, the transistor FET2 includes the gateelectrode 304 over the insulating layer 843, the gate insulating layer305 covering the gate electrode 304, and a semiconductor layer 308 a anda pair of electrodes 310 a and 310 b over the gate insulating layer 305.The semiconductor layer 308 a is connected to the pair of electrodes 310a and 310 b. The pair of electrodes 310 a and 310 b functions as asource electrode and a drain electrode. The transistor FET2 is coveredwith the insulating layer 312 and the insulating layer 314. One of theinsulating layers 312 and 314 is not necessarily provided. The sensingelement C2 includes the first electrode 11 over the gate insulatinglayer 305, the insulating layer 314 and the insulating layer 852 a overthe first electrode 11, and the second electrode 12 over the insulatinglayer 852 a. The insulating layer 852 b is provided over the secondelectrode 12. The light-blocking layer 847 and the coloring layer 845are provided over insulating layer 852 b. Although an example where thetransistor FET2 overlaps with the light-blocking layer 847 and thesensing element C2 overlaps with the coloring layer 845 is shown here,one embodiment of the present invention is not limited to this example.For example, both the transistor FET2 and the sensing element C2 mayoverlap with the light-blocking layer 847.

In one embodiment of the present invention, the semiconductor layer ofthe transistor and the electrode of the sensing element are preferablyformed in the same step, in which case the number of steps forfabricating the input/output device can be reduced, and the fabricationcost can be reduced.

For example, an oxide semiconductor can be used for the semiconductorlayer of the transistor. An oxide semiconductor layer has a highlight-transmitting property. By increasing oxygen vacancies and/orimpurities such as hydrogen or water in the oxide semiconductor layer,an oxide semiconductor layer having a high carrier density and a lowresistance (also referred to as oxide conductor layer) is obtained. Suchan oxide semiconductor layer can be favorably used as the electrode ofthe capacitor of the touch sensor.

Specifically, plasma treatment is performed on an island-like oxidesemiconductor layer that is to be the first electrode 11 to increaseoxygen vacancies and/or impurities such as hydrogen or water in theoxide semiconductor layer; thus, the oxide semiconductor layer can havea high carrier density and a low resistance.

A typical example of the plasma treatment performed on the oxidesemiconductor layer is plasma treatment using a gas containing one of arare gas (He, Ne, Ar, Kr, or Xe), phosphorus, boron, hydrogen, andnitrogen. Specific examples include plasma treatment in an Aratmosphere, plasma treatment in a mixed gas atmosphere of Ar andhydrogen, plasma treatment in an ammonia atmosphere, plasma treatment ina mixed gas atmosphere of Ar and ammonia, and plasma treatment in anitrogen atmosphere.

Furthermore, the insulating layer 314 containing hydrogen is formed incontact with the oxide semiconductor layer to diffuse hydrogen from theinsulating layer containing hydrogen to the oxide semiconductor layer,so that the oxide semiconductor layer can have a high carrier densityand a low resistance. An example of an insulating film containinghydrogen, that is, an insulating film capable of releasing hydrogen is asilicon nitride film.

The insulating layer 312 is provided over the transistor FET2 to preventthe semiconductor layer 308 a from being subjected to the plasmatreatment. Since the insulating layer 312 is provided, the semiconductorlayer 308 a is not in contact with the insulating layer 314 containinghydrogen. By using an insulating film capable of releasing oxygen as theinsulating layer 312, oxygen can be supplied to the semiconductor layer308 a. The semiconductor layer 308 a to which oxygen is supplied is ahigh-resistance oxide semiconductor in which oxygen vacancies in thefilm or at the interface are reduced. As the insulating film capable ofreleasing oxygen, a silicon oxide film or a silicon oxynitride film canbe used, for example.

As described above, the input/output device of one embodiment of thepresent invention achieves both thinness and high detection sensitivityby using an active matrix touch sensor. Furthermore, providing alight-emitting element with an auxiliary electrode suppresses a voltagedrop of the electrode of the light-emitting element and reducesunevenness in display luminance.

The auxiliary electrode is formed in the same step as another conductivefilm, whereby the auxiliary electrode can be formed without an increasein the number of steps.

In the input/output device of one embodiment of the present invention, aconductive film having high wettability to the material of a bondinglayer is provided in contact with the bonding layer. Therefore, entry ofair bubbles can be prevented when the bonding layer attaches a pair ofsubstrates to each other, so that the substrates can be attached with ahigh yield.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 4

In this embodiment, an input/output device of one embodiment of thepresent invention will be described with reference to a drawing.

As has been described in Embodiment 1 and the like, the first conductivelayer that is in contact with a bonding layer when the bonding layerfills a space between the first substrate and the second substratepreferably has high wettability to the material of the bonding layer.High wettability to the material of the bonding layer can reduce airbubbles that enter when the first substrate and the second substrate areattached to each other, and the substrates can be attached with a highyield. In addition, a light-emitting device or an input/output devicecan have high reliability regardless of whether an auxiliary electrodeis electrically connected to the electrode of the light-emittingelement.

For example, in one embodiment of the present invention, it is possiblethat the second conductive layer (conductive layer 853) is not providedas illustrated in FIG. 13.

Moreover, in one embodiment of the present invention, it is possiblethat the first conductive layer (conductive layer 851) is notelectrically connected to the electrode of the light-emitting element.

In the input/output device, parasitic capacitance is sometimes generatedbetween a wiring or an electrode included in the capacitive touch sensorand a wiring or an electrode included in the pixel. The detectionsensitivity of the touch sensor might be decreased when noise generatedwhile the display element such as the light-emitting element operatestravels to the touch sensor through the parasitic capacitance.

In view of the above, the potential of the conductive layer 851 is setat a constant potential in the input/output device of one embodiment ofthe present invention.

Thus, noise is blocked, and a decrease in the detection sensitivity ofthe touch sensor can be suppressed.

The potential of the conductive layer 851 can be any potential except afloating potential and may be a ground potential, for example.

In light of the above, one embodiment of the present invention is aninput/output device including a first substrate, a first transistor overthe first substrate, a light-emitting element over the first transistor,a bonding layer over the light-emitting element, a first conductivelayer over the bonding layer, a first insulating layer over the firstconductive layer, a second conductive layer over the first insulatinglayer, a second substrate over the second conductive layer, and a secondtransistor and a capacitor between the first conductive layer and thesecond substrate. The light-emitting element emits light toward thesecond substrate. The first transistor and the light-emitting elementare electrically connected to each other. The second transistor and thecapacitor are electrically connected to each other. The first conductivelayer overlaps with the light-emitting element and transmits lightemitted from the light-emitting element. The first conductive layer iselectrically connected to the second conductive layer. The firstconductive layer can be supplied with a predetermined potential. It ispreferred that the second conductive layer be formed on the same planeas and contain the same material as a gate electrode or source and drainelectrodes of the second transistor.

Note that in the input/output device shown in Embodiment 3, the secondelectrode, the first conductive layer, and the second conductive layerare electrically connected to each other; thus, a predeterminedpotential is supplied to the first conductive layer (i.e., the potentialof the first conductive layer is not floating). Consequently, a decreasein the detection sensitivity of the touch sensor can be suppressed.

FIG. 13 is an example of a cross-sectional view of an input/outputdevice in one embodiment of the present invention.

The input/output device in FIG. 13 includes the substrate 801, thebonding layer 811, the insulating layer 813, a plurality of transistors,the conductive layer 857 a, the insulating layer 815, the insulatinglayer 817 a, the insulating layer 817 b, the conductive layer 856, aplurality of light-emitting elements, the insulating layer 821, thebonding layer 822, the spacer 823, the conductive layer 851, theinsulating layer 852 a, the insulating layer 852 b, the conductive layer854, the coloring layer 845, the light-blocking layer 847, theconductive layer 857 b, the conductive layer 857 c, a plurality ofsensing elements, the insulating layer 843, the bonding layer 841, andthe substrate 803. The bonding layer 822, the conductive layer 851, theinsulating layer 852 a, the insulating layer 852 b, the insulating layer843, the bonding layer 841, and the substrate 803 transmit visiblelight.

FIG. 13 shows an example where the conductive layer 851, the conductivelayer 854, the conductive layer 857 b, FPC1, and the connector 825 b areelectrically connected to each other. This structure enables apredetermined potential to be supplied to the conductive layer 851.

As described above, in the input/output device of one embodiment of thepresent invention, a conductive film having high wettability to thematerial of a bonding layer is provided in contact with the bondinglayer. Therefore, entry of air bubbles can be prevented when the bondinglayer attaches a pair of substrates to each other, so that thesubstrates can be attached with a high yield. Furthermore, in theinput/output device of one embodiment of the present invention, aconstant potential can be supplied to the conductive film, therebysuppressing transmission of noise to the touch sensor through parasiticcapacitance and suppressing a decrease in the detection sensitivity ofthe touch sensor.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 5

In this embodiment, a method for manufacturing a flexible light-emittingdevice of one embodiment of the present invention will be described.Note that the manufacturing method described in this embodiment enablesfabrication of a flexible input/output device of one embodiment of thepresent invention by changing a layer formed as a layer to be separated(also referred to as peeled layer).

First, a separation layer 203 is formed over a formation substrate 201,and a layer 205 to be separated (hereinafter referred to simply as alayer 205) is formed over the separation layer 203 (FIG. 14A). Moreover,a separation layer 223 is formed over a formation substrate 221, and alayer 225 to be separated (hereinafter referred to simply as a layer225) is formed over the separation layer 223 (FIG. 14B).

Although an example in which the separation layer is formed to have anisland shape is described here, one embodiment of the present inventionis not limited to this example. In this step, the material of theseparation layer is selected such that peeling occurs at the interfacebetween the formation substrate and the separation layer, the interfacebetween the separation layer and the peeled layer, or in the separationlayer when the peeled layer is peeled from the formation substrate. Inthis embodiment, an example in which peeling occurs at the interfacebetween the separation layer and the peeled layer is described; however,one embodiment of the present invention is not limited to such anexample and depends on materials used for the separation layer and thepeeled layer. Note that in the case where the peeled layer has astacked-layer structure, a layer in contact with the separation layer isparticularly referred to as a first layer.

For example, when the separation layer has a stacked-layer structure ofa tungsten film and a tungsten oxide film and peeling occurs at theinterface between the tungsten film and the tungsten oxide film (or thevicinity of the interface), part of the separation layer (here, part ofthe tungsten oxide film) may remain on the peeled layer. Moreover, theseparation layer remaining on the peeled layer may be removed afterpeeling.

As the formation substrate, a substrate having heat resistance highenough to withstand at least the process temperature in a manufacturingprocess is used. As the formation substrate, for example, a glasssubstrate, a quartz substrate, a sapphire substrate, a semiconductorsubstrate, a ceramic substrate, a metal substrate, a resin substrate, ora plastic substrate can be used.

When a glass substrate is used as the formation substrate, an insulatingfilm such as a silicon oxide film, a silicon oxynitride film, a siliconnitride film, or a silicon nitride oxide film is preferably formed as abase film between the formation substrate and the separation layer, inwhich case contamination from the glass substrate can be prevented.

The separation layer can be formed using an element selected fromtungsten, molybdenum, titanium, tantalum, niobium, nickel, cobalt,zirconium, zinc, ruthenium, rhodium, palladium, osmium, iridium, andsilicon; an alloy material containing any of the elements; a compoundmaterial containing any of the elements; or the like. A crystalstructure of a layer containing silicon may be amorphous, microcrystal,or polycrystal. Furthermore, a metal oxide such as aluminum oxide,gallium oxide, zinc oxide, titanium dioxide, indium oxide, indium tinoxide, indium zinc oxide, or In-Ga-Zn oxide may be used. The separationlayer is preferably formed using a high-melting point metal materialsuch as tungsten, titanium, or molybdenum, in which case the degree offreedom of the process for forming the peeled layer can be increased.

The separation layer can be formed by, for example, a sputtering method,a plasma-enhanced CVD method, a coating method (including a spin coatingmethod, a droplet discharging method, and a dispensing method), or aprinting method. The thickness of the separation layer ranges from 10 nmto 200 nm, for example, and preferably from 20 nm to 100 nm.

When the separation layer has a single-layer structure, a tungstenlayer, a molybdenum layer, or a layer containing a mixture of tungstenand molybdenum is preferably formed. Alternatively, a layer containingan oxide or an oxynitride of tungsten, a layer containing an oxide or anoxynitride of molybdenum, or a layer containing an oxide or anoxynitride of a mixture of tungsten and molybdenum may be formed. Notethat a mixture of tungsten and molybdenum is an alloy of tungsten andmolybdenum, for example.

When the separation layer has a stacked-layer structure including alayer containing tungsten and a layer containing an oxide of tungsten,the layer containing an oxide of tungsten may be formed as follows: thelayer containing tungsten is formed first and an insulating film formedof an oxide is formed thereover, so that the layer containing an oxideof tungsten is formed at the interface between the tungsten layer andthe insulating film. Alternatively, the layer containing an oxide oftungsten may be formed by performing thermal oxidation treatment, oxygenplasma treatment, nitrous oxide (N₂O) plasma treatment, treatment with ahighly oxidizing solution such as ozone water, or the like on thesurface of the layer containing tungsten. Plasma treatment or heattreatment may be performed in an atmosphere of oxygen, nitrogen, ornitrous oxide alone, or a mixed gas of any of these gasses and anothergas. Surface condition of the separation layer is changed by the plasmatreatment or heat treatment, whereby adhesion between the separationlayer and the insulating film formed later can be controlled.

Note that the separation layer is not necessarily provided in the casewhere peeling at an interface between the formation substrate and thepeeled layer is possible. For example, a glass substrate is used as theformation substrate, and an organic resin such as polyimide, polyester,polyolefin, polyamide, polycarbonate, or acrylic is formed in contactwith the glass substrate. Next, adhesion between the formation substrateand the organic resin is increased by laser light irradiation or heattreatment. Then, an insulating film, a transistor, and the like areformed over the organic resin. After that, peeling at the interfacebetween the formation substrate and the organic resin can be performedby performing laser light irradiation with higher energy density thanthe above laser light irradiation or performing heat treatment at ahigher temperature than the above heat treatment. Moreover, theinterface between the formation substrate and the organic resin may besoaked in a liquid to perform peeling.

Since the insulating film, the transistor, and the like are formed overthe organic resin having low heat resistance in the above method, it isimpossible to expose the substrate to high temperatures in themanufacturing process. Note that a transistor using an oxidesemiconductor is not necessarily processed at high temperatures and thuscan be favorably formed over the organic resin.

The organic resin may be used for a substrate of the device.Alternatively, the organic resin may be removed and another substratemay be bonded to an exposed surface of the peeled layer with the use ofan adhesive.

Alternatively, peeling at the interface between a metal layer and theorganic resin may be performed in the following manner: the metal layeris provided between the formation substrate and the organic resin andcurrent is made to flow in the metal layer so that the metal layer isheated.

There is no particular limitation on a layer formed as the peeled layer.For example, to manufacture the light-emitting device illustrated inFIG. 2A, the insulating layer 813, the transistor 820, thelight-emitting element 830, and the like are formed as one of the peeledlayers, whereas the insulating layer 843, the conductive layer 851, theconductive layer 853, the coloring layer 845, the light-blocking layer847, and the like are formed as the other peeled layer.

The insulating layers 813 and 843 formed in contact with the separationlayer preferably have a single-layer structure or a stacked-layerstructure including any of a silicon nitride film, a silicon oxynitridefilm, a silicon oxide film, a silicon nitride oxide film, and the like.

The insulating layers 813 and 843 can be formed by a sputtering method,a plasma-enhanced CVD method, a coating method, a printing method, orthe like. For example, the insulating layer is formed at temperaturesranging from 250° C. to 400° C. by a plasma-enhanced CVD method, wherebythe insulating layer can be a dense film with very high resistance tomoisture. The thickness of the insulating layer ranges preferably from10 nm to 3000 nm, more preferably from 200 nm to 1500 nm.

Next, the formation substrate 201 and the formation substrate 221 areattached to each other with a bonding layer 207 so that surfaces onwhich the peeled layers are formed face each other, and the bondinglayer 207 is cured (FIG. 14C).

Note that the formation substrate 201 and the formation substrate 221are preferably attached to each other in a reduced-pressure atmosphere.

Although FIG. 14C illustrates the case where the separation layer 203and the separation layer 223 have different sizes, the separation layersmay have the same size as illustrated in FIG. 14D.

The bonding layer 207 is provided to overlap with the separation layer203, the layer 205, the layer 225, and the separation layer 223. Theedges of the bonding layer 207 preferably overlap at least one of theseparation layer 203 and the separation layer 223 (the one intended tobe separated first). Accordingly, strong adhesion between the formationsubstrate 201 and the formation substrate 221 can be suppressed; thus, adecrease in yield of a subsequent separation process can be suppressed.

As the bonding layer 207, various curable adhesives such as a reactivecurable adhesive, a thermosetting adhesive, an anaerobic adhesive, and aphotocurable adhesive such as an ultraviolet curable adhesive can beused. Examples of these adhesives include an epoxy resin, an acrylicresin, a silicone resin, a phenol resin, a polyimide resin, an imideresin, a PVC resin, a PVB resin, and an EVA resin. A material with lowmoisture permeability, such as an epoxy resin, is particularlypreferred. For the adhesive, a material having fluidity low enough todispose the material only in a desired region is preferably used. Forexample, an adhesive sheet, a bonding sheet, or a sheet-like orfilm-like adhesive can be used, and an optical clear adhesive (OCA) filmcan be preferably used.

The adhesive may have adhesion before attachment or exhibit adhesionafter attachment by heating or light irradiation.

Furthermore, the resin may include a drying agent. For example, it ispossible to use a substance that adsorbs moisture by chemicaladsorption, such as oxide of an alkaline earth metal (e.g., calciumoxide or barium oxide), or a substance that adsorbs moisture by physicaladsorption, such as zeolite or silica gel. The drying agent ispreferably included, in which case it can suppress deterioration of thefunctional element due to entry of moisture in the air and can improvethe reliability of the device.

Next, a separation trigger is formed by laser light irradiation (FIGS.15A and 15B).

Either the formation substrate 201 or the formation substrate 221 may beseparated first. In the case where the separation layers differ in size,a substrate over which a larger separation layer is formed may beseparated first or a substrate over which a smaller separation layer isformed may be separated first. In the case where an element such as asemiconductor element, a light-emitting element, or a display element isformed only over one of the substrates, the substrate where the elementis formed may be separated first or the other substrate may be separatedfirst. Here, an example in which the formation substrate 201 isseparated first is described.

A region where the cured bonding layer 207, the layer 205, and theseparation layer 203 overlap with each other is irradiated with laserlight (see an arrow P1 in FIG. 15A).

Part of the first layer is removed; thus, the separation trigger can beformed (see a region surrounded by a dashed line in FIG. 15B). At thistime, not only the first layer but also the separation layer 203, thebonding layer 207, or another layer included in the layer 205 may bepartly removed.

Laser light is preferably applied toward the substrate provided with theseparation layer that is desirably peeled. When a region where theseparation layer 203 and the separation layer 223 overlap with eachother is irradiated with laser light, the formation substrate 201 andthe separation layer 203 can be selectively separated by cracking onlythe layer 205 between the layer 205 and the layer 225 (see the regionsurrounded by the dashed line in FIG. 15B. Here, an example in whichfilms of the layer 205 are partly removed is shown).

Then, the layer 205 and the formation substrate 201 are separated fromeach other from the separation trigger (FIGS. 15C and 15D). Thus, thelayer 205 can be transferred from the formation substrate 201 to theformation substrate 221.

For example, the layer 205 and the formation substrate 201 may beseparated from the separation trigger by mechanical force (e.g., apeeling process with a human hand or a gripper, or a peeling process byrotation of a roller).

Alternatively, the formation substrate 201 and the layer 205 may beseparated by filling the interface between the separation layer 203 andthe layer 205 with a liquid such as water. A portion between theseparation layer 203 and the layer 205 absorbs a liquid throughcapillarity action, so that the separation layer 203 can be separatedeasily. Furthermore, an adverse effect of static electricity caused atseparation on the functional element included in the layer 205 (e.g.,damage to a semiconductor element from static electricity) can besuppressed.

Next, the exposed layer 205 is attached to a substrate 231 with abonding layer 233, and the bonding layer 233 is cured (FIG. 16A).

Note that the layer 205 and the substrate 231 are preferably attached toeach other in a reduced-pressure atmosphere.

Subsequently, a separation trigger is formed by laser light irradiation(FIGS. 16B and 16C).

A region where the cured bonding layer 233, the layer 225, and theseparation layer 223 overlap with each other is irradiated with laserlight (see an arrow P2 in FIG. 16B). Part of the first layer is removed;thus, the separation trigger can be formed (see a region surrounded by adashed line in FIG. 16C. Here, an example in which films of the layer225 are partly removed is shown). At this time, not only the first layerbut also the separation layer 223, the bonding layer 233, or anotherlayer included in the layer 225 may be partly removed.

Laser light is preferably applied toward the formation substrate 221provided with the separation layer 223.

Then, the layer 225 and the formation substrate 221 are separated fromeach other from the separation trigger (FIG. 16D). Accordingly, thelayer 205 and the layer 225 can be transferred to the substrate 231.

In the above method for manufacturing the light-emitting device of oneembodiment of the present invention, separation is performed in such amanner that a separation trigger is formed by laser light irradiationafter a pair of formation substrates each provided with a separationlayer and a peeled layer are attached to each other and then theseparation layers and the peeled layers are made in a state whereseparation is easily performed. Thus, the yield of the separationprocess can be improved.

In addition, peeling is performed after the formation substrates eachprovided with the peeled layer are attached to each other in advance,and then, a substrate where a device is intended to be formed can beattached to the peeled layers. Thus, to attach the peeled layers to eachother, formation substrates having low flexibility can be attached toeach other; thus, alignment accuracy at the time of attachment can beimproved as compared to the case where flexible substrates are attachedto each other.

As illustrated in FIG. 17A, the edge of the layer 205 to be separated ispreferably positioned on the inner side of the edge of the separationlayer 203, in which case the yield of the separation process can beimproved. When there are a plurality of layers 205 to be separated, theseparation layer 203 may be provided for each layer 205 as illustratedin FIG. 17B or a plurality of layers 205 may be provided over oneseparation layer 203 as illustrated in FIG. 17C.

This embodiment can be combined with any other embodiment asappropriate.

Embodiment 6

In this embodiment, electronic devices and lighting devices that can befabricated according to one embodiment of the present invention will bedescribed with reference to FIGS. 18A to 18G and FIGS. 19A to 19I.

The light-emitting device and the input/output device of one embodimentof the present invention are flexible and thus are preferably used in aflexible electronic device and a flexible lighting device. According toone embodiment of the present invention, an electronic device and alighting device that have high reliability and high resistance torepeated bending can be achieved.

Examples of electronic devices include a television set (also referredto as television or television receiver), a monitor of a computer or thelike, a camera such as a digital camera and a digital video camera, adigital photo frame, a mobile phone (also referred to as a cellularphone or mobile phone device), a portable game machine, a portableinformation appliance, an audio reproducing device, and a large gamemachine such as a pachinko machine.

The light-emitting device and the input/output device of one embodimentof the present invention have flexibility and therefore can beincorporated along a curved inside/outside wall surface of a house or abuilding or a curved interior/exterior surface of a car.

An electronic device of one embodiment of the present invention mayinclude an input/output device and a secondary battery. In that case, itis preferred that the secondary battery be capable of being charged bynon-contact power transmission.

Examples of the secondary battery include a lithium ion secondarybattery such as a lithium polymer battery using a gel electrolyte(lithium ion polymer battery), a nickel-hydride battery, anickel-cadmium battery, an organic radical battery, a lead-acid battery,an air secondary battery, a nickel-zinc battery, and a silver-zincbattery.

An electronic device of one embodiment of the present invention mayinclude an input/output device and an antenna. Receiving a signal withthe antenna enables a display portion to display video, information, andthe like. When the electronic device includes a secondary battery, theantenna may be used for non-contact power transmission.

FIG. 18A illustrates an example of a mobile phone. A mobile phone 7400is provided with a display portion 7402 incorporated in a housing 7401,an operation button 7403, an external connection port 7404, a speaker7405, a microphone 7406, and the like. The mobile phone 7400 ismanufactured using the light-emitting device or the input/output deviceof one embodiment of the present invention for the display portion 7402.According to one embodiment of the present invention, a highly reliablemobile phone having a curved display portion can be provided with a highyield.

When the display portion 7402 of the mobile phone 7400 in FIG. 18A istouched with a finger or the like, data can be input to the mobile phone7400. Operations such as making a call and inputting letters can beperformed by touch on the display portion 7402 with a finger or thelike.

With the operation button 7403, the power can be turned on and off.Furthermore, types of images displayed on the display portion 7402 canbe switched; for example, the image can be switched from a mail creationscreen to a main menu.

FIG. 18B illustrates an example of a wrist-watch-type portableinformation appliance. A portable information appliance 7100 includes ahousing 7101, a display portion 7102, a band 7103, a buckle 7104, anoperation button 7105, an input/output terminal 7106, and the like.

The portable information appliance 7100 is capable of executing avariety of applications such as mobile phone calls, e-mailing, readingand editing texts, music reproduction, Internet communication, and acomputer game.

The display surface of the display portion 7102 is curved, and imagescan be displayed on the curved display surface. The display portion 7102includes a touch sensor, and operation can be performed by touching thescreen with a finger, a stylus, or the like. For example, an applicationcan be started by touching an icon 7107 displayed on the display portion7102.

With the operation button 7105, a variety of functions such as timesetting, power on/off, on/off control of wireless communication, settingand cancellation of manner mode, and setting and cancellation of powersaving mode can be performed. For example, the functions of theoperation button 7105 can be set freely by the operating systemincorporated in the portable information appliance 7100.

The portable information appliance 7100 can employ near fieldcommunication, which is a communication method based on an existingcommunication standard. In that case, for example, hands-free calling isachieved with mutual communication between the portable informationappliance 7100 and a headset capable of wireless communication.

Since the portable information appliance 7100 includes the input/outputterminal 7106, data can be directly transmitted to and received fromanother information appliance via a connector. Charging through theinput/output terminal 7106 is possible. Note that the charging operationmay be performed by wireless power feeding without using theinput/output terminal 7106.

The display portion 7102 of the portable information appliance 7100includes the light-emitting device or the input/output device of oneembodiment of the present invention. According to one embodiment of thepresent invention, a highly reliable portable information appliancehaving a curved display portion can be provided with a high yield.

FIGS. 18C to 18E illustrate examples of lighting devices. Lightingdevices 7200, 7210, and 7220 each include a stage 7201 provided with anoperation switch 7203 and a light-emitting portion supported by thestage 7201.

The lighting device 7200 illustrated in FIG. 18C includes alight-emitting portion 7202 with a wave-shaped light-emitting surfaceand thus has a sophisticated design.

A light-emitting portion 7212 included in the lighting device 7210 inFIG. 18D has two convex-curved light-emitting portions symmetricallyplaced. Thus, all directions can be illuminated with the lighting device7210 as a center.

The lighting device 7220 illustrated in FIG. 18E includes aconcave-curved light-emitting portion 7222. This is suitable forilluminating a specific range because light emitted from thelight-emitting portion 7222 is collected at the front of the lightingdevice 7220.

The light-emitting portion included in each of the lighting devices7200, 7210, and 7220 is flexible; accordingly, the light-emittingportion may be fixed on a plastic member, a movable frame, or the likeso that a light-emitting surface of the light-emitting portion can bebent freely depending on the intended use.

Although the lighting devices in which the light-emitting portion issupported by the stage are described as examples, a housing providedwith a light-emitting portion can be fixed on a ceiling or suspendedfrom a ceiling. Since the light-emitting surface can be curved, thelight-emitting surface can be bent concavely so that a particular regionis brightly illuminated, or bent convexly so that the whole room isbrightly illuminated.

Here, each of the light-emitting portions includes the light-emittingdevice or the input/output device of one embodiment of the presentinvention. According to one embodiment of the present invention, ahighly reliable lighting device having a curved light-emitting portioncan be provided with a high yield.

FIG. 18F illustrates an example of a portable input/output device. Aninput/output device 7300 includes a housing 7301, a display portion7302, operation buttons 7303, a display portion pull 7304, and a controlportion 7305.

The input/output device 7300 includes a rolled flexible display portion7302 in the cylindrical housing 7301.

The input/output device 7300 can receive a video signal with the controlportion 7305 and display the received video on the display portion 7302.The control portion 7305 includes a battery. Moreover, the controlportion 7305 may include a terminal portion for connecting a connectorso that a video signal or power can be directly supplied from theoutside through a wire.

By pressing the operation buttons 7303, power on/off, switching ofdisplayed video, and the like can be performed.

FIG. 18G illustrates the input/output device 7300 in a state where thedisplay portion 7302 is pulled out with the display portion pull 7304.Video can be displayed on the display portion 7302 in this state. Theoperation buttons 7303 on the surface of the housing 7301 allowone-handed operation. The operation buttons 7303 are provided not in thecenter of the housing 7301 but on one side of the housing 7301 asillustrated in FIG. 18F, which makes one-handed operation easy.

A reinforcement frame may be provided for a side portion of the displayportion 7302 so that the display portion 7302 has a flat display surfacewhen pulled out.

Note that in addition to this structure, the housing may be providedwith a speaker so that sound is output with an audio signal receivedtogether with a video signal.

The display portion 7302 includes the light-emitting device or theinput/output device of one embodiment of the present invention.According to one embodiment of the present invention, a lightweight andhighly reliable input/output device can be provided with a high yield.

FIGS. 19A to 19C illustrate a foldable portable information appliance310. FIG. 19A illustrates the portable information appliance 310 that isopened. FIG. 19B illustrates the portable information appliance 310 thatis being opened or being folded. FIG. 19C illustrates the portableinformation appliance 310 that is folded. The portable informationappliance 310 is highly portable when folded, and is highly browsablewhen opened because of a seamless large display area.

A display panel 316 is supported by three housings 315 joined togetherby hinges 313. By folding the portable information appliance 310 at aconnection portion between two housings 315 with the hinges 313, theportable information appliance 310 can be reversibly changed in shapefrom an opened state to a folded state. The light-emitting device or theinput/output device of one embodiment of the present invention can beused for the display panel 316. For example, it is possible to use alight-emitting device or an input/output device that can be bent with aradius of curvature of 1 mm or more and 150 mm or less.

In one embodiment of the present invention, a sensor that senses whetherthe light-emitting device or the input/output device is folded or openedand supplies sensing information may be provided. When obtaininginformation indicating that the light-emitting device or theinput/output device is folded, a control portion of the light-emittingdevice or the input/output device may stop a folded portion (or aportion that is folded and cannot be seen by a user) from operating,specifically performing display or sensing by a touch sensor.

Similarly, the control portion of the light-emitting device or theinput/output device may make display and sensing by a touch sensorrestart when obtaining information indicating that the light-emittingdevice or the input/output device is opened.

FIGS. 19D and 19E illustrate a foldable portable information appliance320. FIG. 19D illustrates the portable information appliance 320 that isfolded so that a display portion 322 is on the outside. FIG. 19Eillustrates the portable information appliance 320 that is folded sothat the display portion 322 is on the inside. When the portableinformation appliance 320 is not used, the portable informationappliance 320 is folded so that a non-display portion 325 faces theoutside, whereby the display portion 322 can be prevented from beingcontaminated or damaged. The light-emitting device or the input/outputdevice of one embodiment of the present invention can be used for thedisplay portion 322.

FIG. 19F is a perspective view illustrating the external shape of aportable information appliance 330. FIG. 19G is a top view of theportable information appliance 330. FIG. 19H is a perspective viewillustrating the external shape of a portable information appliance 340.

The portable information appliances 330 and 340 function as one or moreof a telephone set, an electronic notebook, and an information browsingsystem, for example.

Specifically, each of the portable information appliances 330 and 340can be used as a smartphone.

The portable information appliances 330 and 340 can display letters andimage data on their plurality of surfaces. For example, three operationbuttons 339 can be displayed on one surface (FIGS. 19F and 19H).Moreover, information 337 indicated by dashed rectangles can bedisplayed on another surface (FIGS. 19G and 19H). Examples of theinformation 337 include notification of a social networking service(SNS) message, display indicating reception of an email or an incomingcall, the title or sender of an email or the like, the date, the time,remaining battery, and the reception strength of an antenna.Alternatively, the operation button 339, an icon, or the like may bedisplayed in place of the information 337. Although FIGS. 19F and 19Gshow the example in which the information 337 is displayed at the top,one embodiment of the present invention is not limited to this example.For instance, the information 337 may be displayed on the side as in theportable information appliance 340 in FIG. 19H.

For example, a user can see the display (here, the information 337) withthe portable information appliance 330 put in a breast pocket.

Specifically, a caller's phone number, name, or the like of an incomingcall is displayed at a position that can be observed from above theportable information appliance 330. Thus, the user can see the displaywithout taking out the portable information appliance 330 from thepocket and decide whether to answer the phone.

The light-emitting device or the input/output device of one embodimentof the present invention can be used for a display portion 333 includedin a housing 335 of the portable information appliance 330 and a housing336 of the portable information appliance 340. According to oneembodiment of the present invention, a highly reliable portableinformation appliance having a curved display portion can be providedwith a high yield.

As in a portable information appliance 345 illustrated in FIG. 19I,information may be displayed on at least three surfaces. Here, as anexample, information 355, information 356, and information 357 aredisplayed on different surfaces.

The light-emitting device or the input/output device of one embodimentof the present invention can be used for a display portion 358 includedin a housing 354 of the portable information appliance 345. According toone embodiment of the present invention, a highly reliable portableinformation appliance having a curved display portion can be providedwith a high yield.

This embodiment can be combined with any other embodiment asappropriate.

This application is based on Japanese Patent Application serial no.2014-095140 filed with Japan Patent Office on May 2, 2014, the entirecontents of which are hereby incorporated by reference.

What is claimed is:
 1. A light-emitting device comprising: a firstsubstrate; a light-emitting element over the first substrate; a firstconductive layer over the light-emitting element; a first insulatinglayer over the first conductive layer; a second conductive layer overthe first insulating layer; and a second substrate over the secondconductive layer, wherein the light-emitting element comprises a firstelectrode over the first substrate, a light-emitting layer over thefirst electrode, and a second electrode over the light-emitting layer,wherein the second electrode, the first conductive layer, and the secondconductive layer are electrically connected to each other, and whereinthe first conductive layer and the second electrode are configured totransmit light emitted from the light-emitting element.
 2. Thelight-emitting device according to claim 1, wherein a resistance of thesecond conductive layer is lower than a resistance of the secondelectrode.
 3. The light-emitting device according to claim 1, whereinthe first conductive layer comprises a metal oxide layer, and whereinthe second conductive layer comprises a metal layer.
 4. Thelight-emitting device according to claim 1, further comprising a bondinglayer between the light-emitting element and the first conductive layer.5. The light-emitting device according to claim 1, wherein the firstsubstrate and the second substrate are flexible.
 6. The light-emittingdevice according to claim 1, further comprising a first transistorbetween the first substrate and the light-emitting element, wherein thefirst transistor is electrically connected to the light-emittingelement.
 7. The light-emitting device according to claim 1, furthercomprising a coloring layer between the first insulating layer and thefirst conductive layer, wherein the coloring layer overlaps with thelight-emitting element.
 8. The light-emitting device according to claim1, further comprising a first light-blocking layer between the firstinsulating layer and the first conductive layer, wherein the firstlight-blocking layer overlaps with the second conductive layer.
 9. Thelight-emitting device according to claim 1, further comprising a secondlight-blocking layer between the second substrate and the firstconductive layer, wherein the second light-blocking layer overlaps withthe second conductive layer.
 10. The light-emitting device according toclaim 1, further comprising a second insulating layer, wherein an endportion of the first electrode is covered by the second insulatinglayer, and wherein the first conductive layer is in contact with thesecond electrode in a region overlapping with the first insulatinglayer.
 11. An input/output device comprising: the light-emitting deviceaccording to claim 1; and a sensor portion comprising a capacitor,wherein the light-emitting device and the sensor portion overlap witheach other.
 12. An input/output device comprising: a first substrate; afirst transistor over the first substrate; a light-emitting element overthe first transistor; a first conductive layer over the light-emittingelement; a first insulating layer over the first conductive layer; asecond conductive layer over the first insulating layer; a secondsubstrate over the second conductive layer; and a second transistor anda capacitor between the first conductive layer and the second substrate,wherein the first transistor and the light-emitting element areelectrically connected to each other, wherein the second transistor andthe capacitor are electrically connected to each other, wherein thefirst conductive layer overlaps with the light-emitting element, whereinthe first conductive layer is configured to transmit light emitted bythe light-emitting element, wherein the first conductive layer iselectrically connected to the second conductive layer, wherein thesecond conductive layer is formed on a same plane as a gate electrode orsource and drain electrodes of the second transistor, and wherein thesecond conductive layer comprises a same material as a material of thegate electrode or the source and drain electrodes of the secondtransistor.
 13. The input/output device according to claim 12, furthercomprising a bonding layer between the light-emitting element and thefirst conductive layer.
 14. The input/output device according to claim12, wherein the light-emitting element comprises a first electrode overthe first substrate, a light-emitting layer over the first electrode,and a second electrode over the light-emitting layer, and wherein thesecond electrode is electrically connected to the first conductivelayer.
 15. The input/output device according to claim 12, wherein thelight-emitting element is configured to emit light toward the secondsubstrate.
 16. The input/output device according to claim 12, whereinthe first conductive layer comprises a metal oxide layer, and whereinthe second conductive layer comprises a metal layer.
 17. Theinput/output device according to claim 12, wherein the first conductivelayer is configured to be supplied with a predetermined potential. 18.The input/output device according to claim 12, wherein the firstsubstrate and the second substrate are flexible.
 19. The input/outputdevice according to claim 12, further comprising a coloring layerbetween the first insulating layer and the first conductive layer,wherein the coloring layer overlaps with the light-emitting element. 20.The input/output device according to claim 12, further comprising afirst light-blocking layer between the first insulating layer and thefirst conductive layer, wherein the first light-blocking layer overlapswith the second conductive layer.
 21. The input/output device accordingto claim 12, further comprising a second light-blocking layer betweenthe second substrate and the first conductive layer, wherein the secondlight-blocking layer overlaps with the second conductive layer.